Cylinder head stud.

Hi, I took my Fabia into a local garage for a full service and an Mot two weeks ago, and prior to this the car was running well. 51 miles later I noticed that I had difficulty starting, but once started it ran sweetly. I took the car back to the same garage who did the Mot and I was told that this is a common problem and it would be caused by the timing chain. I searched the symptons and thought that it maybe the coolant temp sensor but the mechanic said no.I left the car with them and asked for a price for the work but at the time they were unable to tell me. I telephoned three days later to check on progress and they told me that a cylinder head gasket and a valve had been ordered as the car was not firing on 1 cylinder. The next day I telephoned again and was told that they had snapped a stud  and that they could not remove it as it is solid in the block. Now I am left with no car and finance to pay. Can anyone advise?  Only had car 8 months and its on a 3 year arrangement. Thanks