Eu preciso contestar esta cobrança indevida.

Yes, you can usually leave it out.

Portuguese often drops subject pronouns when the verb form already makes the subject clear. So both of these are natural:

• Eu preciso contestar esta cobrança indevida.
• Preciso contestar esta cobrança indevida.

Including eu can add emphasis, contrast, or just make the sentence a little more explicit. In everyday Brazilian Portuguese, both versions are common.

Here, preciso is the first-person singular form of the verb precisar, which means to need.

So:

• precisar = to need
• eu preciso = I need

Be careful not to confuse this with the adjective preciso, which can mean precise or exact in other contexts.

In this sentence, it is clearly the verb:

• Eu preciso contestar... = I need to dispute/challenge...

Because after precisar, Portuguese normally uses another verb in the infinitive.

Structure:

• precisar + infinitive

Examples:

• Preciso sair. = I need to leave.
• Preciso estudar. = I need to study.
• Preciso contestar esta cobrança indevida. = I need to dispute this improper charge.

This works much like English need to + verb.

Contestar means to contest, to dispute, or to challenge something, especially when you believe it is wrong, unfair, or invalid.

In billing, legal, or administrative contexts, contestar is very common. It sounds appropriate and natural for disputing a charge.

For example:

• contestar uma cobrança
• contestar uma multa
• contestar uma decisão

So in this sentence, it means something like formally challenge/dispute this improper charge.

Often, yes.

Cobrança comes from the verb cobrar, which means to charge, to bill, or sometimes to collect payment.

Depending on context, cobrança can mean:

• a charge
• a billing
• a collection demand
• the act of charging someone

In this sentence, cobrança is best understood as charge or billing charge.

So:

• uma cobrança indevida = an improper charge / an incorrect billing charge

Both can be correct, but they reflect a small difference in deixis, and in real Brazilian Portuguese the distinction is often relaxed.

Traditional grammar:

• esta = this, near the speaker
• essa = that, near the listener or already mentioned
• aquela = that over there, farther away

In modern Brazilian Portuguese, essa is often used where traditional grammar might expect esta, especially in speech. So many Brazilians would naturally say:

• Preciso contestar essa cobrança indevida.

That may sound even more common in everyday conversation.

So:

• esta cobrança = perfectly correct
• essa cobrança = also very common and natural in Brazil

Because indevida is an adjective describing cobrança, and it has to agree with the noun in gender and number.

• cobrança is feminine singular
• so the adjective must also be feminine singular: indevida

Compare:

• cobrança indevida = improper charge
• pagamento indevido = improper payment

So:

• feminine noun → indevida
• masculine noun → indevido

Indevida means something like:

• improper
• undue
• wrong
• unauthorized
• not justified

In billing language, cobrança indevida usually refers to a charge that should not have been made.

It is a very common expression in customer service, banking, and consumer protection contexts in Brazil.

Because in Portuguese, adjectives often come after the noun.

So:

• cobrança indevida literally follows the pattern
• charge improper

This is normal in Portuguese.

Sometimes adjectives can come before the noun, but that often changes the tone, emphasis, or sounds less neutral. In this case, cobrança indevida is the standard and natural order.

It is natural, and it sounds especially appropriate in a customer service, legal, banking, or complaint context.

It is not overly stiff, but it is more formal than casual speech because of words like:

• contestar
• cobrança indevida

In a more casual situation, someone might also say:

• Preciso reclamar dessa cobrança.
• Preciso questionar essa cobrança.

But contestar esta cobrança indevida sounds very good if you are speaking to a company, bank, or support agent.

Sometimes, yes, but the meaning shifts a little.

• contestar = to formally dispute or challenge
• reclamar = to complain
• questionar = to question
• discutir a cobrança = sometimes to dispute it, depending on context

If your goal is to say you want to officially challenge the charge, contestar is the best choice.

Compare:

• Preciso contestar esta cobrança indevida. = I need to dispute this improper charge.
• Preciso reclamar desta cobrança indevida. = I need to complain about this improper charge.

So reclamar is possible, but it is not exactly the same.

Yes. In fact, that is probably one of the most natural everyday Brazilian versions.

• Preciso contestar essa cobrança indevida.

Why it sounds very natural:

• dropping eu is common
• essa is very frequent in Brazilian speech
• the rest of the sentence is clear and idiomatic

So the original sentence is correct, but this version may sound a bit more conversational in Brazil.

A rough pronunciation guide is:

• cobrança ≈ koh-BRAN-sah

Key points:

• ç sounds like s
• ã is nasal, so it is not a plain a sound
• the stress is on bran

So:

• co-bran-ça

The nasal vowel in bran is one of the trickier parts for English speakers. Try not to pronounce it like a fully separate an in English; it should sound more nasal and smoother.

No article is missing.

In Portuguese, a demonstrative like esta, essa, or aquela can directly modify the noun:

• esta cobrança
• essa cobrança
• aquela cobrança

You would only add a preposition if the sentence required one. For example:

• Vou responder a esta cobrança. = I’m going to respond to this charge.
• Reagi a essa cobrança. = I reacted to that charge.

But in your sentence, contestar takes the object directly:

• contestar esta cobrança

So no extra preposition is needed.