Pathetic service still waiting for the car over 5 months later

This has been the worst service that we have ever received. Our Opel Astra has been with them since May and all they do is order incorrect parts. The car went in cause it had a problem with the car was overheating and it has been downhill since then of course they have made us pay for all these parts which seem to me that they have messed up in the car.