Worse ISP ever

Hi, I requested cancellation in Jan and submitted my notice from the customer portal,and now I'm being advised that the service will only cancel end of April. This people is taking my money and I canceled already months ago. I will log a formal complaint if another debit order is processed as this is unacceptable to not honor your own policy for cancellation. They offered me a discount when I submitted the cancellation so why is it now that they saying I did not cancel. I WILL NEVER TAKE ANY SERVICES FROM THEM OR REFER THEM TO ANYONE