USELESS and POOR Customer Service

I have resigned membership (policy ***) via email on Monday 2 March (1 March was a Sunday) on behalf of my pensioner Mother, Mrs. C.E Putter seeing that she doesn't have access to internet or email. On 11 March someone woke up at the call centre and send an email that her policy will only be cancelled by 30 April instead of 31 March. THIS IS NOT ACCEPTABLE. We have given 30 day notice from 1 March to 31 March. She has resigned because she CAN NO longer afford the monthly premium being a state pensioner. This morning again she got an sms that her policy has been activated!! Seriously this is honestly shocking. She cannot AFFORD one payment going through anymore. Can someone on management level please take charge of this and provide me with feedback ASAP.