who do i contact about being charged for an app i did not purchase?!

I have just found a billing email addressed to me saying i have purchased an app and that i will be charged £59.99 to my bank account. I have did not purchase this app and i have no idea how it has ended up on my phone. The email tells me that £23.64 will be taken from my store credit and £36.35 from my bank. What the **** do i do?! what phone number can i contact apple on? i will contact my bank and report fraud but i cannot find a number on the apple website regarding these situations!