Upgrade without my concent

I've been an MTN contract customer for almost 10 years. 2 Months ago I was eligible for an upgrade, but I wanted to wait for a better device. Last week I walked into an MTN store to finally choose a better device than my current one, but they couldn't help me because they changed my contract to a sim only in Feb without my concent and changed my upgrade date to 2021. They told me I need to call the customer care line so that they can do a reversal of the contract. Why is something so simply taking so long to action? I didnt even tell them that I want to switch over to a sim only contract OR upgrade my contract at that time.

Why should I wait another 2 years to be able to choose a new device for an upgrade they did without my concent . Why cant they never help you in store with something like this. Why do you always have to phone the customer care line where they cant even help you because they query needs to be sent to the "back office" where you cant call anyone becuase they only correspond via email.

Now I have to run around with a faulty device and hope that this issue gets resolved without knowing exactly whats happening... All I get is the generic "It can take up to 24 - 72 hours to resolve"