How to stop Quick Quid taking payment from my debit card?

Hello all, last week in a moment of madness we took out a �400 quick quid loan because we needed money asap ( our car needed to be fixed urgently ) , but family could help us and paid for it, now I am trying to cancel the loan and they are saying no, I am pretty sure that in the agreement I have a right to cancel within 14 days. I have gone onto my bank account online and deleted the direct debit set up for them so they cannot take any money, will this stop them? Am I also in my right to cancel? Wish I never bothered now , big mistake. Thanks