Unauthorized charges

I play an online game ( mobile strike) on July 14 I purchased 2 game packs, 1@$99.99 and 1@$49.99 and I received them. When I got my receipt and looked at what Apple charged me they had charged for an additional 3@$99.99 and 1@$49.99 that I did not authorize or receive. I have gone through the on line process to get my money back and I have called them twice. They refuse to return my money. This is theft pure and simple of my $350. They refuse to even give me a reason why they won’t return my money. This is my last attempt at resolving this before I go and file against them. Just because they are a big corporation doesn’t mean they can do anything they want and steal peoples money