Jumping through hoops to not renew a contract

My contract was due to expire in April 2018. I did not know the exact date. I sent an email to MTN requesting the date that the contract was expiring and in the same email that I did not want to renew ( ********** 6). They rep**** with the expiry date of ********** 0. On ********** 8 I queried whether the contract was not renewed. On ********** 9 I was told I had to complete a cancellation form and supply a copy of my ID. This was never mention in the 16 March reply. Today I get an email "We have escalated your cancellation request to our cancellations team to contact and assist you further. Please note that all cancellation requests require a 30 days notice." When I queried what the difference is between "not renewing" and cancellation is, I got this email "Kindly note when you mention you are not renewing the contract it goes on a month to month contract , cancellation request is when you wish the number to be deactivated /placed on pre-paid . This will only be done when all the documents are received ." I am trying to understand how not renewing moves the contract onto a month to month contract.