Προτιμώ χρεωστική κάρτα, όχι πιστωτική κάρτα ή προπληρωμένη κάρτα.

Because Greek usually drops subject pronouns when they are not needed.

The verb Προτιμώ already means I prefer, so εγώ is unnecessary unless you want extra emphasis, contrast, or clarity.

• Προτιμώ χρεωστική κάρτα = I prefer a debit card
• Εγώ προτιμώ χρεωστική κάρτα = I prefer a debit card

The second version sounds more like contrast, as in I prefer debit card, but someone else may not.

Προτιμώ is the 1st person singular present tense of προτιμώ.

So it means:

• I prefer
• I am preferring in a general present sense

It is a very common verb for expressing preference.
If you want to sound more polite or softer, Greek often uses:

• Θα προτιμούσα... = I would prefer...

Greek can sometimes omit the article in short, practical, choice-based statements like this, especially when the speaker is naming a type/category rather than talking about one specific card.

So:

• Προτιμώ χρεωστική κάρτα sounds like I prefer debit card / a debit card
• Προτιμώ τη χρεωστική κάρτα sounds more like I prefer the debit card

In everyday Greek, both patterns can occur, but the version without the article can sound a bit more like a quick real-life choice statement, especially in a payment context.

Because they describe κάρτα, and κάρτα is a feminine noun in Greek.

Greek adjectives must agree with the noun they describe in:

• gender
• number
• case

So because κάρτα is feminine singular, the adjectives are also feminine singular:

• χρεωστική κάρτα
• πιστωτική κάρτα
• προπληρωμένη κάρτα

If the noun were masculine or neuter, the adjective form would change.

Because it comes from a different adjective pattern.

• χρεωστική and πιστωτική are adjectives of the -ικός / -ική / -ικό type
• προπληρωμένη is from the participle/adjectival pattern -μένος / -μένη / -μένο

So:

• χρεωστικός / χρεωστική / χρεωστικό
• πιστωτικός / πιστωτική / πιστωτικό
• προπληρωμένος / προπληρωμένη / προπληρωμένο

This is very common in Greek: some adjectives are ordinary descriptive adjectives, while others come from participles and mean something like prepaid, written, closed, open, etc.

Yes, Greek could leave it out after the first mention.

For example:

• Προτιμώ χρεωστική κάρτα, όχι πιστωτική ή προπληρωμένη.

That is perfectly understandable.

But repeating κάρτα:

• adds clarity
• sounds more explicit
• avoids any chance of confusion

So the repeated version is not wrong at all; it is just fuller and clearer.

Because δεν normally negates a verb, while όχι can negate or reject a word, phrase, or option.

Here the verb is not being negated. The speaker is not saying:

• I do not prefer

Instead, the speaker is correcting or excluding other choices:

• not credit card or prepaid card

So όχι is the natural choice.

Compare:

• Δεν προτιμώ πιστωτική κάρτα. = I do not prefer a credit card.
• Προτιμώ χρεωστική κάρτα, όχι πιστωτική κάρτα. = I prefer debit card, not credit card.

Here ή means or.

It is different from η, which is the feminine singular definite article the.

The accent mark is important:

• ή = or
• η = the (feminine)

They are pronounced the same in Modern Greek, so in writing the accent is what tells you which one it is.

They are in the accusative, because they are the direct object of Προτιμώ.

You prefer something, so that thing is in the accusative.

However, in this sentence, the feminine singular forms look the same as the nominative in many cases:

• χρεωστική κάρτα
• πιστωτική κάρτα
• προπληρωμένη κάρτα

If you added the article, the accusative would be easier to see:

• τη χρεωστική κάρτα
• την πιστωτική κάρτα
• την προπληρωμένη κάρτα

So yes, grammatically these are objects, even though the forms do not change much visibly.

It can change. Greek word order is fairly flexible, though some orders sound more natural than others.

The given sentence is natural and clear:

• Προτιμώ χρεωστική κάρτα, όχι πιστωτική κάρτα ή προπληρωμένη κάρτα.

But you could also say things like:

• Χρεωστική κάρτα προτιμώ, όχι πιστωτική ή προπληρωμένη.
• Όχι πιστωτική κάρτα ή προπληρωμένη· προτιμώ χρεωστική κάρτα.

Changing the order usually changes the focus or emphasis, not the core meaning.

Yes. The comma is natural because it separates:

• the preferred option from
• the rejected alternatives

So the structure is roughly:

• I prefer X, not Y or Z

In speech, you would usually hear a short pause there too.

A simple pronunciation guide would be:

Pro-ti-MO hreo-STI-ki KAR-ta, O-hi pi-sto-TI-ki KAR-ta i pro-pli-ro-ME-ni KAR-ta.

A few notes:

• Προτιμώ has the stress on the last syllable: -μώ
• χ in χρεωστική is like a rough h/k sound, not an English ch
• ή is just ee
• όχι is O-hi, not like English okey

Yes, it is understandable and usable, especially if you are contrasting card types.

But in a real shop or restaurant, Greek speakers might also say something a little more directly tied to payment, such as:

• Θα πληρώσω με χρεωστική κάρτα. = I’ll pay by debit card.
• Προτιμώ να πληρώσω με χρεωστική κάρτα. = I prefer to pay by debit card.

So your sentence is correct, but in real life the version with με + card type may sound even more natural when the topic is the payment method rather than the card type itself.

Yes. Greek often uses αλλά όχι for a stronger contrast:

• Προτιμώ χρεωστική κάρτα, αλλά όχι πιστωτική ή προπληρωμένη.

This sounds like:

• I prefer a debit card, but not a credit or prepaid card.

The original sentence without αλλά is still fine. It is just a bit more direct and compact.