I've never had any problems with Mojo warranty. They have always sorted stuff out for all the guys i know that have had problems – even had a set of Fox 40 lowers replaced just because there was a newer model that they deemed to be better!! FOC!
Under consumer law, it is down to Fox to prove that you hadn't serviced the forks every 5 mins. That'd be difficult as they cant prove how long you ride for. Call up ranting & raving and i have no doubt they wont help, call up politely & they will always help out.
If the bikes come from Si @ progressive with the forks fitted then thats fine. If he is selling them separately then no warranty.
J