Theft from Netstar

Netstar over charged me through a monthly debit orderand I contacted them and they promised to refund me but that did not happened instead I am running after them for my money. I have decided to cancel the contract because if this company can take money from my account and then I must fight for it then their dont care about me as their customer and not going to pay cancellations penalties because I am not the one at fault but Netstar.