at the risk of sounding even more daft, can't you weld up where the leaks are on the intercooler?
ah, what about getting the plastic replaced with some metal? probably not feasable mind just thinking out loud so to speak
is yours split in the same place as the one you just bought? might be worth seeing if you can make one decent cooler out of the two broken ones you have?
fingers crossed
Why not have a custom one made up.http://www.grsmotorsport.co.uk/customintercoolers.html