heaters, fiat punto 54 plate. 3dr active?

Hi, I had a problem where my fan for my heater was just not switching on. The air is warm, but the fan would. I took it to an electronics motor place. And instead of putting a new heater in they put a fuse in to bi-pass the system. This worked for a week but the fuse blew. I went back and they put a larger fuse in, This two burnt out and when having my car serviced the mechanic told me that the electric people has cut the wires to short so even if i but new motor now. They cant say it will definatly work. In the summer this is ok but in winter real problem. Any advise???