HELP -> Krótka odpowiedź na list

Cześć! Muszę odpisać na list w sprawie rachunku za leczenie za granicą. Czy ktoś mógł by mi pomóc przetłumaczyć końcówkę, bo nie wiem jak to poprawnie napisać.


"Dear Madam,
I am writing in response to your letter advising of an unpaid bill for a medical treatment of my daughter in your hospital. There must have been some mistake. I would like to inform you that I have paid 50 Euro as an excess of amount at 10.8.2006. (Na dowód tego załączam potwierdzenie. Oczekuję szybkiego wyjaśnienia sprawy i przeprosin. Z poważaniem…)"

>"Dear Madam,
>I am writing in response to your letter advising of an unpaid bill for
>a medical treatment of my daughter in your hospital. There must have
>been [some]A mistake. I would like to inform you that I [have] paid 50 [Euro] euros Z MALEJ LITERY I L. MNOGA
>[as an excess of amount] TO ZNACZY ZE NADPLACILAS 50 EUROS??? JESLI TAK TO POWYZEJ JAKIEJ SUMY?; MUSISZ PODAC SUME atON 10.8.2006. (Na dowód tego załączam
>potwierdzenie. Oczekuję szybkiego wyjaśnienia sprawy i przeprosin. Z
>poważaniem

DWIE WERSJE:
1.nadplacilas o 50 euros
Dear Madam,
I am writing in response to your letter advising of an unpaid bill for
a medical treatment of my daughter in your hospital. There must have
been a mistake. I would like to inform you that I have paid 50 euros
as an excess of the amount of [suma powyzej ktorej nadplacilas] on 10.8.2006.
I'm enclosing a receipt as a proof of my payment. I'm looking forward to a prompt rectification of my account and apology.
Yours faithfully

2. zaplacilas rachunek na 50 euros:
Dear Madam,
I am writing in response to your letter advising of an unpaid bill for
a medical treatment of my daughter in your hospital. There must have
been a mistake. I would like to inform you that I have paid my bill in the amount of 50 euros on 10.8.2006.
I'm enclosing a receipt as a proof of my payment. I'm looking forward to a prompt rectification of my account and apology.
Yours faithfully

Bardzo dziękuję za pomoc :)