Bad Service

I was using WebAfrica but due to an ongoing issue with my router that could not be sorted by their technicians I decided to move ISP.I gave them notice in April and was told I needed to give a full month's notice which I accept as fair.However in July I start getting a debit on my account which they now say is because I never gave sufficient notice so am still liable.It does not explain why I'm being debited for Aug,Sept.I have chatted through bots and agents on WhatsApp but the issue is not being resolved and receive no feedback.When I follow up on my query I need to start the query over resend bank statements etc to prove that I am being debited yet nothing gets resolved.Why get a reference number when it means nothing. Does the accounts department not have records.This is so disappointing.Please I would appreciate some feedback.