bardzo proszę o wykrycie błędów i skorygowanie :)

Dear Sir or Madame
I bought fortnight your shop computer. It cost 3500Euro. I have trouble with this product. Computer don't work when I turn it on. Now, when I turn it on is only black screen. I ask to my friend in repair. He is worker. I'm afraid don't secceed, although he consultant from workmate. I await of You arrival to my home and repair computer, and all this is guarantee.
XYZ

Dear Sir or MadaM,
'I bought fortnight' (to co napisales to jest 'Ja kupilem dwa tygodnie' to niemasz na mysli - o czym mysisz to jest Dwa tyg temu ja kupilem - prosze napisac to zdanie w ten sposob) IN your shop A computer. It cost 3500Euro. I have HAD trouble with this product. Computer 'don't' DOES NOT work when I turn it on. Now, when I turn it on THERE is only A 'black' (mowimy BLANK) screen.
I askED (czas przeszly -ed) 'to' (niepotr) my friend 'in' (niepotr) TO repair IT. 'He is A worker' (ale gdzie?- czy mam zgadywac) . I'm afraid HE 'don't' DID NOT (czas przeszly) 'secceed' (ortog), although he consultED 'from' HIS workmate. I await 'of' (niepotrz) youR arrival 'to' AT my home and THE repair OF THE computer, 'and' (tutaj uzyj AS) all this is guaranteeD.