Cannot get through security on facebook

Hello,
Pleeeease someone help!
My Ex lost my IPhone recently and now conviently I can't log into my facebook
It keeps coming up with a security question I've seen in my life (my first teachers name) which I can Definitely say I have NEVER had that as a question I no
my 2 security questions by heart,
Anyways please help me it's driving me mad! Lol