KO & Sanwa - what Receiver?

[BelstenToo]

I have both a Sanwa Gemini 2 & a KO Vantage Esprit 2 and neither transmitter wants to talk to the other brand of receiver (and yes I have swapped the xtals over!)

Anyone have any idea why this could be or if it's the case that they just won't work together then what budget receiver would work with either or both transmitters?
I'd rather use the one transmitter for my cars and don't want the hassle of swapping one receiver between them.