Dialdirect continues to deduct a premium!!!

I sold my vehicle on 28/01/2019, and called Dialdirect to cancel my policy on the same day. The gentleman I spoke to reassured me that my policy including any other products related to the policy had now been cancelled. Four months later Dialdirect VAP continues to deduct a premium from my bank account. I have sent them two e-mails requesting that they stop deducting a premium and that they refund me for all the months that they have been deducting money from me. They haven't bothered to respond to me or to my request, and have once again deducted money from me this month. I have never received such bad service from any other insurance company. I would advise any people considering to insure their vehicle to steer clear of this company. I have had nothing but terrible service from them.