kia sportage 2001

ia have 2001 kia sportage with me . i went for technical inspection 3 time always rear brake weak.i adjusted the brake from mattar qadeam car max shop with the same machine they have in technical inspection.i went back and they return my money i said sorry.then i went to another mechanic he said brake drum need to be changed ,i changed the both drum ,but the problem is still there.there is no light on the dash board like abs or some other warning light.any one can help me regarding this .dont tell me to go kia company they are very costly .any help .thanks