MTN MANIPULATIVE SCHEMES

I had a contract with mtn last year which was one parkage with two cellphones which ended in November, before end of November I received few Sms's telling me my contract is ending month end and I have an option to renew it "they even called me and I declined.. They deducted end of November and I was alright with it because I know I have signed a 2year deal with them. End December they deducted again And I called early January and they told me I was supposed to have called and requested cancelation "I didn't understand that because me and them know our contract is 2 years but I said it's fine I want to cancel, they transferred me to cancelation which didn't pick up for days I tried until they picked up around the 9th of January and I did cancel and got a Ref number. They opted my phone to prepaid and kept the other one on contract which I saw when it received airtime. They combined my laptop installment and the an amount they came across without informing me for the airtime given on the other phone, now they are telling me I was supposed to call on that number and cancel the contract. I reversed the instalment they took for March and they blocked my laptop Rutter and the other number, I don't get it what gives them a right to my bank account to change amounts as they want and hold me in this airtime data contract that I never agreed to . I called them and went to mtn store in pta church street but no help. I believe this people are manipulating me to debt and their customer service is useless.