Holden Astra 2001: Engine warning light coming on regularly

Late last year my 2001 Holden Astra was running well, but badly in need of servicing and the timing belt needed replacement (122,000 km). My brother-in-law said his repairer, Kmart, was quite good and as I didn't have a regular repairer, went there. I have had problems ever since with the engine warning light coming on regularly and have been back on a number of occasions. A computer check indicated that it needed a new crank sensor, which was replaced, but the warning light still came on. An auto electrician they called in said that as the timing belt was an aftermarket one the teeth didn't mesh properly until the belt had stretched a bit. The mechanics were happy with the explanation, and I left happy as a result. The warning light still comes on, and a few days ago it went into “Limp Mode”. I drove home about 35km and to the repairer who scoffed at the auto electrician's explanation as if he had never heard it before. After computer checks the next day I was told that it is the transmission and they would now like to take it to a Holden dealer. I have asked them on a couple of occasions to look at the timing belt, but am not having much luck and the car is very unreliable and not driveable at present.

Yesterday, I went to see a friend of mine, who is a retired mechanic, and he checked the car and said that he doesn't believe that it is the transmission and that it is the timing belt. I would appreciate a reply if you could as I am at my wits end.