Don't forget the subwoofers are not a standard impedance, so make sure a replacement amp will drive them.
My Carver DSP amp got wet, but I dried it out and cleaned it, and it's worked fine for 12 months plus.
The likes of ECU testing can probably repair the amp for a fraction of the new price - DON'T use BBA-Reman...
I'd be getting it repaired/swapping for a used one as it's a lot of hassle replacing the Carver DSP with an aftermarket setup, and unless you are spending big £, it probably won't sound as good.
Mike