I brought an Audi A3 from a garage about 130 miles away from home. Within the first week I noticed the car had very little power and so I called the garage and they said to bring it back, they would diagnose and fix the problem. They kept the car for 3 hours and then called to ask if I could leave it with them for a couple of days as they had to order a catalytic converter. I asked them about covering my travel expenses as I needed a car for work and they refused, but did say the car was fine to drive and they would call me when the part was in, so I took the car away. The following week I called and was told the part was in on Wednesday. When I called back to comfirm I would be in Friday to have it fitted, I was then told the part wasn't in and it would be in the next day and they would call me to confirm once it was in. By 4.30pm on Thursday and I hadn't heard from them, so I called and was put on hold for someone to check. They came back to me and said the mechanic was out and they would call me once he was back. An hour and half later I still hadn't received a call and so I called back and was put on hold for 15 mins whilst they were checking if the part was in. I was told the wrong part was delivered and they would be getting it Friday morning. The car has gradually been getting worse and I am too worried to continue driving it. Does anyone know how long I have to give the garage, legally before I can exercise my rights under the sale of goods act and reject the car for a refund?