Yep bypassing is a piece of p!ss to do, the matrix in my gf's driver failed on saturday. Driving along the M11 pulled off on a slip road when we stopped what I thought was smoke started billowing out of the dash!!! Got her to pull over quick and switch car off, popped bonnet and the 'smoke' was now coming out under the bonnet aswell. Quickly grabbed screwdriver out of the boot and frantically started stripping the dash down expecting something to go up in flames any second. Got as far as removing the heater fan and noticed it was wet and everything finally clicked!!! Went back for another sniff of the 'smoke' and discovered it was steam. Quick trip to B&Q for some 20mm copper pipe and a hacksaw, bit of emergency plumbing and we were back on our way!
Looks like I'll be fitting a new matrix before the winter!!!