However from reading many threads on the YourNav forum, it seems the quality of their support can be very variable. I suppose it depends on who you get dealing with your problem.
My personal experience: I bought a new 920T this Tuesday. The following day I tried to update the maps, using the free 30 day latest maps guarantee. Using TomTom Home, it said I had the latest maps, which was not the case. I telephoned TomTom support, and was told that if I faxed them a copy of the sales receipt they would arrange for me to be able to download the latest maps. This I did immediately.
I am STILL waiting to be able to do this.