Plea to cancel a deal

The customer's interaction was perfect however they are worse in delivering the product. I was sold a car which had technical issues and when I returned it they accepted without any complain. They were supposed to cancel the deal because it was still within 5 days of signing the contract. The sales person convinced me to take another car, which I told him I need to exercise my options at other dealers. When I got a better offer somewhere same dealership but different branch, I realised they did not cancel the 1st deal from their side. I wrote to their dealer principal and have not received any acknowledgement of my email.