Klient dzwoni niezależnie od tego, czy odczyt licznika wzrósł, czy spadł.

It means regardless of whether ..., or ....

In this sentence:

• niezależnie od tego = regardless of that / regardless of the fact
• czy ..., czy ... = whether ..., or ...

So the whole pattern is:

niezależnie od tego, czy X, czy Y
= regardless of whether X or Y

This is a very common Polish structure. Another close equivalent is:

• bez względu na to, czy ... czy ...

Both mean essentially the same thing.

Because od requires the genitive case, and to changes to tego in the genitive.

So:

• to = this/it/that
• after od → tego

The phrase niezależnie od tego is a fixed, very common expression meaning regardless of that / regardless of whether.

Learners often want to translate word for word, but it is best to remember the whole chunk:

niezależnie od tego, czy ...

as one unit.

It is the same word, but here it has a different function.

In questions, czy can mean whether / if:

• Czy on przyjdzie? = Will he come?

In your sentence, czy is a subordinating conjunction, not a question marker. It introduces alternatives:

• czy odczyt licznika wzrósł, czy spadł
• whether the meter reading increased or decreased

So here czy ... czy ... works like whether ... or ....

Because Polish usually expresses X of Y by putting Y in the genitive case after the noun.

So:

• odczyt = reading
• licznik = meter
• licznika = genitive singular of licznik

Therefore:

• odczyt licznika = the reading of the meter = meter reading

This is a very common Polish pattern:

• numer telefonu = phone number
• drzwi domu = the house’s door / the door of the house
• kolor auta = car color

Because it depends on the noun odczyt.

In Polish, when one noun specifies another, the second noun is often in the genitive. English often uses of for this:

• odczyt licznika = reading of the meter
• koniec filmu = end of the film
• początek dnia = beginning of the day

So licznika is genitive singular because it means of the meter.

Because they agree with the subject odczyt.

The subject of both verbs is:

• odczyt licznika = the meter reading

The head noun is odczyt, and odczyt is masculine singular, so the past tense verb must also be masculine singular:

• odczyt wzrósł
• odczyt spadł

If the subject were feminine, you would get a feminine form:

• temperatura wzrosła
• temperatura spadła

If it were plural:

• ceny wzrosły
• ceny spadły

Because they refer to a completed change: the reading went up or went down.

Polish often uses the past tense in a sentence like this when talking about the result of some earlier event. The main clause is in the present:

• Klient dzwoni = The customer calls / is calling

but the thing that does not matter is whether, before that, the reading increased or decreased:

• wzrósł
• spadł

So the sentence means that the customer calls in either case, no matter which of those two past outcomes happened.

Yes. Dzwoni can mean either:

• is calling
  or
• calls

Polish present tense often covers both the English simple present and present continuous, depending on context.

So:

• Klient dzwoni can mean The customer is calling
• or The customer calls

In a general statement like this, English often translates it as The customer calls. In a real-time situation, it could also mean The customer is calling.

Because the subject is the same for both verbs: odczyt licznika.

Polish, like English, often avoids repeating the subject when it is clearly understood.

So:

• czy odczyt licznika wzrósł, czy spadł

means:

• whether the meter reading increased or decreased

Just like in English, you do not need to say:

• whether the meter reading increased, or the meter reading decreased

The shorter version is more natural.

They are perfective past forms.

• wzrosnąć → past: wzrósł
• spaść → past: spadł

Perfective verbs show a completed event or single change. That fits this sentence well, because the reading either went up or went down as a result.

If you used imperfective verbs, the meaning would be different or less natural here:

• rósł = was rising / used to rise
• spadał = was falling / used to fall

Those would suggest an ongoing process rather than the finished outcome. Here Polish wants the completed result.

Usually not if you mean the final outcome.

• wzrósł / spadł = increased / decreased as completed changes
• wzrastał / spadał = was increasing / was decreasing or used to increase / decrease

Your original sentence is about whether the reading ended up higher or lower. That strongly favors the perfective forms:

• wzrósł
• spadł

Using wzrastał / spadał would shift the meaning toward an ongoing process and would sound less natural in this context.

Yes, to some extent. Polish word order is flexible, though not completely free.

The original:

• Klient dzwoni niezależnie od tego, czy odczyt licznika wzrósł, czy spadł.

You could also say:

• Niezależnie od tego, czy odczyt licznika wzrósł, czy spadł, klient dzwoni.

This version puts more focus on the regardless of whether... part first.

Both are correct. The original sounds very natural.

Not here.

• czy ... czy ... = whether ... or ...
• albo ... albo ... = either ... or ...

In this sentence, you need the structure that matches niezależnie od tego and introduces two possibilities under whether. So:

• niezależnie od tego, czy X, czy Y is correct

Using albo ... albo ... here would not sound natural.

Yes. The preposition od takes the genitive case.

Examples:

• niezależnie od pogody = regardless of the weather
• niezależnie od sytuacji = regardless of the situation
• niezależnie od tego = regardless of that / regardless of whether

So in your sentence, the genitive in tego comes from the preposition od.

Here licznik means meter, such as an electricity meter, gas meter, or similar device that records usage.

So:

• odczyt licznika = meter reading

Be careful, because licznik can also mean counter in other contexts, depending on what is being counted or measured.

It is basically neutral, maybe slightly on the formal/administrative side because of the phrase odczyt licznika and the structure niezależnie od tego, czy....

It sounds natural in customer-service, technical, billing, or utility-company contexts.

A more conversational sentence might use a simpler structure, but your original sentence is fully normal and correct.