Audi Dealership does not have Audi parts and poor workmanship

i took my vehicle to audi braamfontien for repairs that needed to be done as well as the 120000km service - this was the beginning of December. the service i received from this "5 star" dealership was appalling. the vehicle was towed to their dealership on Monday the 5th Dec and i received the vehicle back the Friday afternoon after 4. it took them a week to replace a door cable, a gearbox pipe (they waited a week for) and do a service, their excuse, they did not have stock of parts. besides the long wait, the workmanship was appalling. they did a service but neglected to check wiper blades or brakes and i had grease stains in my door armrest. the best part, they did not have stock of spark plugs (R1100) for my vehicle, they advised they would contact me once the plugs arrived, till today i have not heard from them. i paid more than R15000 at this dealership for poor workmanship and appalling service. i will never use this dealer ever again.