Problem canceling a policy

I've app**** for pet insurance, and then I informed the insurance that I want to cancel, due to the fact that I don't have the funds available anymore. I've sent numerous emails, but the debit order (amount changes every month) keeps on going (or trying to go through) on my bank account. I tried to cancel the debit order through the bank, but the advised me to contact Outsurance. It's incurring bank fees for each debit order that doesn't go through, and it looks very bad for my credit rating.