Peter Fletcher's dashboard

Can anyone tell me if their is a genuine problem with the car charger for the Tom Tom 910.
I have sent mine away twice for repair and they have replaced the unit, which caused major problem with the maps I had purchased.
Anyway my second replacement has now developed the same problem and won't turn on, there is a smell of smomething burnt.
Surely Tom Tom should have know of this problem, recalled and replaced the faulty chargers.
My Tom Tom seems to have been for repair more than I've used it.
I use an old Magellan Roadmate when it's in for repair, never let me down.
Really fed up with this unit, are the more expensive ones any better?