Hi Veester.
If your
direct debit agreement is Cancelled by the bank ( either by yourself or an error by the bank) or NU were unable to take funds it is possible that your policy will be cancelled due to non payment.
However, normally 2 warning letters are sent BEFORE a Notice of cancellation is sent. Did you not recieve any of these?
Have you moved address recently and forgotten to inform NU?
In response to your comments about paying for nothing, I'm presuming the fee paid was your deposit? therefore this charge will have covered you for 2 months of insurance. ( no cancellation fee applies if NU cancel your policy due to non payment of dd's - they simply cancel from your paid upto date)
Hope this helps, When you called up the first time ( when you advise there were no issues with the dd) what were you informed?