I have a Defender 180Xtreme which broke down last week. The Land Rover specialist (not a dealer) who is mending it - I've not used them before - says the ECU is to blame, it is completely dead and doesn't respond and he has to fit a new one. I asked for the original one back to see if I can get it mended, but he says he has to send it back to Land Rover - that if you get a new one, the broken one goes back. This sounds very dubious to me, especially as the original one had been chipped. Should I believe them?