Unsatisfactory client service

About two years ago I took out a home-based router with MTN,is was an online deal which was handled telephonically and the device was delivered to a desired address.After having the contract for about more than a year I've enquired about the possibility of early termination whereby I was informed that it's not possible,as there is still a few months remaining on my contract and that the amount payable for the device would be high,as a result of this I continued paying my normal monthly instalment,which went off by debit order,However in the month of April,the instalment was higher,more than double the normal amount,I went into the store aswell as called the customer care,neither was really helpful and I ended up paying so as to avoid getting a bad credit record.It was only at that point I was informed my contract ended in April 2024,however the contract was upgraded or changed to a month to month option resulting in a higher instalment without my knowledge,bearing in mind no invoices were received for the previous,even though the payment went off.After contacting the customer line again,to cancel the contract I was informed since it's month to month,the contract will terminte a month from the date of the intent of cancellation,however I will still have to pay for that current month,barring in mind my top up date is the 17th and the debit order date is the 20th.With this being my "last month"I received another ridiculous bill which is more than double my instalment,and still not sure what it's for the customer care champion as well as the shop assitant informed me the higher amount is only for April I am appalled by this service,as this is a *******,as no one bothered to inform/remind me when the contract would end,and went about instating a higher charge without my concent According to MTN,a customer should know when their contract ends and cancel a month prior to that date,to avoid further chargers,however these terms were NEVER COMMUNICATED!!!