How do I get itunes to stop charging me for a app that I never ordered.

I have been charged by itunes for $1.07 on my debit card for a long time there are months that I don't have any money in the bank so my bank charges me $29.00 every time this happens. I am sick to my stomach over the reoccurring charge. I have tried many times to stop itunes from charging me but I get the biggest run-around. This charge has been going on for two years or more. I need help. I am crying while I am typing this.