Eastvaal Motors Witbank

Husband oderd a weathers strip for my car, only to find out it was mot the strip that was faulty sowe went back to dealership and requested that they should do a refund because we no longer need the wheather strip, manager said they can assist us only if we are willing to pay 15%penalty fee and pay and amount of R350 for courier to send item back to Suzuki, my question is, is it fair for dealer ship to take back 50% of amount spent just because the item was ordered? To me this is just total reap off