hi pam, it sounds very much like cable damage on the rear door where it goes through a grommet into the body of the bongo. we had the same on ours, had to strip out the rear panel of the tailgate, pull out the wires and put new in, all joints heatshrunk, shouldnt take you too long to do, i did a factsheet in the members area with regards to this. hope your handy with a soldering iron.
seriously ive got a lot of auto electrics to do, waycar8 and di and jamies alarm to do so if your not too much in a hurry could do the whole lot together over half a day
it would take a while to do pam but im certainly up for helping you especially with flapjack on offer.