I'd have suggested just programming a new key...
MK5 Feesties use PATS 2 immobiliser. They're mega straightforward to code a new key to, and much less hassle than changing all the locks, ecu etc.

Get a decent auto locksmith to code all the original, or even the new parts with diagnostic software.
I use FoCom for pumps, injectors, PCM coding... and It does key programming too.