Not canceled as requested

Hi. So i have a contract for data. But it ended in December. In November I called to cancel it and give 1 months notice. No I was told I need to call on 9th December. I called ND canceled the contract. Then on January I noticed it hadn't been canceled so I called again to cancel it. That's 3 months on a row!!!! Today in February 2020 it is still not canceled. And they took money in January. I am disgusted at the poor service. Now I call ND they always experiencing high call volumes. And they cut you off!!!!