franny

Hello, I have been driving a C4 VTR+ diesel on a 56 plate. I have had 4 years trouble free driving until now. I booked my car in for a service and it had a weird noise coming from one of the belts.. Had no idea which one. The day I took the car in the noise had stopped. The garage have since rang me to say the noise was being made by the alternator free wheel pulley, which had sheared off. He ordered a new pulley and set about replacing it only for his tool kit (SX400) not to actually fit its a spline bit sop I am told. So I have called the local dealership spoke to someone on the service reception who went and spoke to a mechanic. I was then told you cant replace it you have to have a whole new alternator. Which seems odd as if it cant be replaced why can you buy the part? Has anyone had any experience of this issue? All helo would be greatly appreciated. If there are mods on this site that think this should be moved to a technical area please move as appropriate. Regards Lee