Clarity of Procedures that MTN follows

My mum has taken out a 36 month contract with MTN which comes to an end November this year. When an online enquiry was done it showed that an upgrade can be done from the 14 July 2025. According to an MTN contact centre agent the upgrade can only be done in November when the contract ends. If an upgrade is done this month it means that we would need to pay for the upgrade plus the contract that ends in November. We want to upgrade the same contract that ends in November 2025. Please explain how the upgrades works with MTN as my understanding or my previous experience of an upgrade is that once upgraded the old contract falls away and start paying for the upgrade.

Then my mum was going to change one of the other contracts that she has with MTN , the contact centre agent sends her an sms which she must approve giving MTN permission to debit her at a maximum amount and this excludes the amount that would need to be paid each month. Please explain what all of this is as it’s a cash contract for which it’s paid eft each month.

Your urgent feedback will be much appreciated.