Wont stop expired contract

I have been trying since Oct 2015 to stop a debit order going down from my bank account ( of which the contract had already expired earlier in the year). I went in twice , got a reference number and gets the process which happens to take about a month started , only to get another invoice at the end of each month! This is ridiculous!! What happened to freedom of will? If I am free to choose to start using a product , should I not be free to choose to stop as well? But the company simply disregards your voice as client and decides for you!!!