is it legal to cancel without prior notice??

I telephoned my insurance company and explaining that I had LOST MY JOB IN APRIL. I REQUESTED THE BANK TO CANCELL THE DEBIT ORDER,however the insurance company continued deducting money from my account. This gave me assurance that should anything happen to my car I would still be covered. In October the debit bounced according to them but i was never informed of this instead the insurance was automatically cancelled.Can they legally cancel without prior notice? I dont undertstand this I feel it is unfair to me as I did a decent thing of informing them however they could not do the same. Please someone explain this to me. I am very dissapointed that an insurance company is not something you can depend on.