Just picked up my 645ci yesterday and am more than happy with it, however when I took it for a test drive prior to buying it a warning message came up saying rear fog light failure, I put it on the garages list of things to do prior to picking it up and when I collected it the warning had gone and the mechanic stated it was just a loose wire. Today the warning has reappeared, I am presuming it is probably the bulb and was going to change it myself to save a journey back to the garage however having read some threads it would appear the whole rear bumper needs to come off to change a bulb!!! is this correct??