Not able to upgrade

I have been due to upgrade since the start of February. Every time i get to an MTN the keep telling me that they are busy migrating and I cannot upgrade. I have been trying every month with no success. At this point it feels easier to cancel the contract. I keep paying monthly but get no service in return. They also cannot provide an answer as to when I will be able to upgrade. This is not acceptable and is leaving a very bad taste.