Stick your head between your legs and kiss your arse goodbye. You have no protection other than what is written in your contract. Even that is not ironclad as all they need to do is give you a written or verbal policy change that is applicable to everybody under contract and you don't have a leg to stand on. Best thing you can do is find the easiest way to depart without costing you too much. Or, if you are independently wealthy, you can try to sue them, but why would you want to stay at a company that would believe someone else without trying to find out the truth of the matter? Sounds like you might be a glutton for punishment.
What's unfair dismissal anyway? Company consolidates, downsizes, is affected by the economy, finds you are not the proper "fit" into their corporate culture, etc., etc., yadda, yadda, yadda. Not much you can do about it.
SOME PEOPLE TRY TO TURN BACK THEIR ODOMETERS. NOT ME. I WANT PEOPLE TO KNOW WHY I LOOK THIS WAY. I'VE TRAVELED A LONG WAY, AND SOME OF THE ROADS WEREN'T PAVED. ~ Will Rogers