Did u get the antenna adaptor from eBay? Cheapest I can find is £15
The SEAT units are a pain to decode. I bought a SEAT one as I wanted everything to light up red. The VW ones have a blue screen. However when I went to all my local decoding places they all said the same thing, can't decide the SEAT units, just the VW. Not sure why but my advice would be to stick to a VW one.
Regarding the quadlock, I have a 57 plate FR and the 310 won't power up. Wasn't really aware of this but it definitely is the case for pre facelift Leon's. A local car entertaininment
store should be able to do it for you. Basically I think one of the pins is missing in the quadlock and a live 12v feed needs to be fed to it to power the unit up. That's as much as I know really.
Anything else, just give us a shout