Hi Meisrich,
I think you need to get proper advice fast.
I used to work for a pension provider and looked into employers who "didn't behave themselves"!
You've not provided any reasons for their actions, which would be really helpful as the best thing to do next really depends on this. Actions could be as diverse as "call the fraud squad" to "do nothing at all".
If you can let me know what's happened and why, I'm very happy to talk further. You don't need to give pounds and pence, just the situation. If you're not happy to put that on the forum, say so and (assuming this doesn't break the rules) I'll give you my email address.
Moderator - email allowed in profiles only please, not on the open forum.
mr tom.