Let me know if you find some off a mk2 ZS... Am looking for a spare set of the fog light surrounds/holders for a little project I want to do!
Failing that, do a search on ebay for "MG ZS Fog"... There's a whole page full of them... Expect to pay £30 though!
I replaced one of mine with a 400 unit, was an exact fit and worked great, no soldering required!