Upgraded yet i was chargd out of bundle rate - Disgusting

I upgraded 8 Dec 2020 ref ***3- Followed up on the15th Dec, someone promised it was approved- I should wait for the call for delivery till now i never received any calls. on the 4Jan they change my contract to month to month because i didn't upgrade in time.. can you imagine my shock. As if that wasn't enough. On the 17th Jan they gave me a bill of 1468 that i owe them yet my contract was R480 monthly - numerous calls were made, and visited the Glen branch. Accumulated different references querying the bill ***, & another 1-*** &*** &***. Until some MTN consultant advised i should cancel the contract to avoid further billing on the 4th Feb which I did, but I'm still querying the incorrect billing as matter of Principle-i did my part upgraded in time, MTN processed my upgrade approved it and cancelled thereafter without advising me. Now I'm left a with a bill and nobody explain why they charge out bundle yet i upgraded in time, This one I'm taking to ombudsman.