I have a vauxhall vectra estate 2.2L and my petrol flap wont open!anyone know any tricks to open it?

I have a vauxhall vectra estate and the pertol flap no longer opens! it is controlled by the key fob. The fob is working as my central locking is working! Anyone got any tricks to get it to work. Im desperate as I cant refuel until it works and I dont fancy the bill from vauxhall to do a diagnostics check to tell me it needs fixing!