my in car dvd player wont wont play dvds properly. ?

my double din dvd player for my car wont play dvds properly, its as if your digi box for your tv has a bad signal, ive sent it back to the supplyer in china but as u can imagine its costing too much to send it there so i need it fixed here, some times it dosent play cds either i'm willing to pay some 1 to fix it. this is starting to anoy me i want it fixed lol.
thanks.
rory