Pathetic Customer Service

I purchased a car in December, 1 hour after I picked the car up it started giving issues and making a noise, so i contacted the person who sold me the car and he advised that i bring the car back so they can have a look and do repairs... the car was sitting in their work shop for a month and a half before they gave it back to me, I then only had the car for 3 days and it was still giving issues so they agreed to take the car back and settle the bank... so I've paid an installment on a car I no longer have its been 3 weeks since they said they will settle the car and nothing has been done