cancel contract not canceled

<p>i have maild mr Price mobile to cancel a contract. they mailed back with a setelment amount and cancelation fee. i have paid it and forward the POPmail. that was 1april 2016. after that no debit order was deducted and i asumed it was canseled as i paid. only 6months later for them to start deducting again saying that they did not get my mail. and that the card was in use. yes the card is still in that phone but not using it as i have a BB witch i use. the phone must be updating what ever, but now they want me to pay another canselation fee and pay my normal installment??? what am i to do??? how can they see my request for setelment on my id number they can see i have done the payment but they can not see the POP mail?? very convenient.</p>