2001 Mitsubishi Diamante wipers, windshield & visibility problems

Abnormal smell coming from vents, made me, and my two sons feel nauseous, created a headache for me. I had to open windows in order to drive car due to fumes. Brought car to dealer, and heater core was identified as problem and needed to be replaced. Dealer said this is a very common problem with this year and model. I asked if there was a manufacturer recall and he said no, they only had to do a recall if it was a safety problem. This cost $802.37 to repair. This is most definitely a safety issue.

Heater coil replacement. Causes car to overheat, also causes bad smell and heat and fumes to come out of the dash. It has come to my attention that a large amount of mitsubishi diamantes up to year 2001 have this problem and it has not be considered a recall. I wanted to know why and how this issue can be fixed. It's not fair that customers have to pay over 1000. To get something fixed that is obviously a manufacturer problem. This is not an optional fix since it can ultimately cause an engine fire.