Bad treatment after they keep taking my money

I entered into a contract with the device support. The contract was for 2 years. I pay without any hassles and after my contract ended, they call trying to enter me into another contract. I explain that my previous contract has lapsed but they continue to take money from me. They hang up on me after I explained my frustration and they refused to put me through their supervisor. I went to the branch but they say that they are not linked with the device department. I am frustrated because my money keeps being deducted unnecessary