Billing issues.

A year ago I got a 12 month discount from MWEB which would have expired Feb 2020, in December I called them to downgrade my package as I do not want to pay the full amount. I spoke to the consultant and he advised I will only be billed for my new package in Feb. I even received an email stating I have been moved to the lower package. Now they are still billing me for the old package while I have been using the new (Lower) package. I spoke to a lady early today and she advised she would call me back shortly, I am still waiting on a call and to why I am being billed for the old product. I am not willing to pay for something I did not use.