No service and poor customer support

Since I migrated to MTN in January 2022, I have encountered issues with my number - sometimes when people call me the line will "ring" on their side and eventually go to voicemail, however my device will never receive the call. If I am lucky, I will get a nice SMS afterwards saying that I received a voicemail, yet my phone never rang. This is highly frustrating.

I have contacted MTN numerous times regarding this is issue, however they are unable to provide a resolution. Every time I phone the operator will advise about some sort of a USSD code that I need to run, switch off the phone for 5 min and it should be resolved when the device is turned on - only that it have not work once.

I migrated to MTN with the hopes of that it is better than my previous cellphone service provider, however it seems like they are even worst.