I have a big problem with my Ford Mondeo diesel. The car is now at my local mechanic's workshop for heater plug replacement. Two of the plugs will not come out and my mechanic is concerned they will snap. He said he can't get a burner in and is going to use some heat method with a new tool he has purchased for this job. I trust the mechanic 100 per cent, but I'm concerned these plugs will not come out and will leave me with a huge bill. Can you offer any advice?