Bad service, none response to emails

It's been over a month since I purchased a vehicle with Webuycars and I am not happy, It's frustrating when communication and assistance are lacking, especially when dealing with post-purchase issues. Just 2 days after I purchased a car in one of their branches and it broke down. This issue was never on their Dekra report, and I went back to the branch where I asked for the manager and they sent their mechanic check the issue and he confirmed that it was the petrol pump. However that branch manager was not helpful. I reported the issue with head office and they contacted me via telephone and email, they promised to assist me if I provide them with a quotation invoice for the petrol pump, till today I have not received any feedback.