i agree ^
its things like this that bite u in the arse, or by the tme you relise youve skipped most probs there there all at once asking for money and it seems pointless, so then for people with not so deep pockets give up!
by all means by pass the heater matrix,
1. to stop the leak if its the matrix
2 to find out if it is indeed the matrix,
then buy a s/h one and when the suns out in a few weeks or days then change it.
mines only blowing cold out the vents, but warm down underneth!!