Poor customer service

I signed contract in September 2016 signed the debit order date to be the 30th of the month.The 1st debit order was supposed to go off in December 2016.The gym since then have been deducting my account on the 25th of the month I reported the matter in January 2017 and they promised to rectify their mistake, since January 2017 upto September they have been deducting on the wrong date I went the several with the bank statement and that my bank is charging me for the unpaid debit orders, I then decided to terminate contract with GYM Company manager at Ghandi Square-Emmanuel offered me 3 month free contract without debiting my account however they went and debit without my authorisation and they are harassing me with sms's and Whatsapp messages that I'm owing.my Reference number D06047Gs