Car issues with 2days of purchase

Bought a car on the 19th of November, my mom bought it. On the 21st the car had a gasket issue. Went to their offices and they said the car would be collected and the problem resolved. On the 23rd the car was collected. On the 25th mom called them asking for an update. The sales guy Camaren provided her with the number of the guy working on the car, guy advised he is awaiting approval and payment from Webuycar. Now mom is being called by some call centre agent asking for the quotation and Mileage of the car. First of they have the car so they should know the mileage, secondly on their dekra report it had stated no issues with the Engine or the coolant , yet two days later we had problems with the same things that were ticked off as fine on the dekra report. There is absolutely no reason why they should be calling my mother back and forth asking for ******* information because they sold a car and **** knowing very well there was an issue. So we must now spend weeks carless yet they received their money immediately. Mom paid cash and the cash was received instantly. It is not our responsibility to be chasing after them to resolve an issue we didn’t create. This is unfair and downright unconstitutional and against CPA and an infringement on moms rights as a consumer. What we want now is a time line a valid timeline about when she will receive her car back or her money back. These useless calls from someone who hasn’t got a clue about what they are doing is an irritation and giving mom unnecessary stress. They should communicate amongst each other (call centre, sales guy and mechanic)and the only call we should be getting is when to collect the car or when the refund will be paid out simple.