My parcel is stuck at receita federal

No other option. You need to make an online account in my imports section. And click on pay, it'll show amount. If u dont agree, make a request for revision there itself. Or pay using credit or debit card, you'll receive it rapidly.

Take the letter to your local Post Office, explain that you haven't received a response, and ask if they can help.

I'm going crazy over this -- I've received quite a few packages from the States & other countries, no problem -- and suddenly there is a 15 Rs charge to be paid before a package will be released .... (I got a notice in the mail telling me this) .... and telling me to go online & pay the 15 Rs ... So, I went online & there were many problems with the web site ... So, after a few days of this, I went to the Post Office &  3 of us worked for an hour trying to get this done ... When payment was (finally) made, I asked when the package would arrive ..........................  2 or 3 more months was the answer.

The charge might stem from Custom Fees.   If you exceeded the threshold  for any shipped item or there is a tax levvied on an import, ten you are on the hook.   

Usually there is a cap on how much you can purchase any item from overseas without incurring on levvied fees.  I recall somewhere BR $ 500,00 or roughly USD $ 125.00

And try to use FEDEX or DHL next time.   PTT Postal sucks.

I agree as to using FedEx or others. Correios has cut back so much that we only have delivery once a week. (Rough on bills due the next day)
I to have just gone to local post office and showed letter and paid customs. They seem to get they package faster at their office than home delivery, but another trip to the post office.