No after sales service

No regestration certificate. 6 weeks after the sale. I don't get any aswer from customer service. I got one consultant on the phone who never phoned back. I now have a car that I can not regester on my name. I paid cash and now webuy cars are ignoring me. They sold me the car, they should give me the regestration certificate!!! The worst is they just ignore me. If you want to buy or sell they are very quick, but after sales service is non existant.