Proszę o sprawdzenie listu formalnego,DZIĘKUJE :)

Dear Sir or Madam,

I am writing to complain about the intensive English courses that you offer.
I enrolled for one of your English courses, but you didn't confirmed reserve.
Two days ago I telephoned to your school, but no-one has arrived the phone for four weeks !, so i left a message on answering machine.
I am worried about that I don't have any information from you because I can't decided when i should depart from Chorzów.
I would be grateful if you could give me a full refund of price a English course.
Nevertheless i hope you will send me some details about my reserve, and proof that.
I would appreciate if my problem was resolved soon

Yours faithfully,

Kate

you didn't confirmed reserve -> you didn't confirm my reservation
I telephoned to your school -> I telephoned your school
no-one has arrived the phone -> no one has answered for four weeks
I am worried about that I don't have -> I am worried that I do not have
I can't decided when i should -> I cannot decide when I should
give me a full refund of price a English course -> refund the price of this course
Nevertheless i hope -> Nevertheless, I hope
about my reserve -> about my reservation
and proof that - udowodnić co?
if my problem was resolved soon - nie jestem pewna czasu

Serdeczne dzięki za pomoc

to complain of - piszesz w koncu formalny list
to complain about - jest spotykane czesciej w mowie, i w tzw informal language

I really aprreciate if my problem is resolved soon.

Właśnie w tym jest problem, dużo mówie potocznie po angielsku, więc pisanie czegoś formalnego jest dla mnie niezłym wyzwaniem :)