Non stop Upgrade calls and SMS's even after I upgraded

Just a note - I have upgraded without a device and DATE and airtime only mid September 2020. To this day I have received MANY SMS's and calls from MTN to remind me that our contracts are due for an Upgrade. Every time we have to remind the caller that we DID in fact upgraded already, we received an sms telling us we DID upgrade although without a device. GOSH - do you not upgrade your system MTN? I have been a loyal customer for YEARS AND YEARS - you have been my 1st Cell Phone contract and I have NEVER changed to another network - yet, I'm truly considering it. Perhaps look into your system please so the system can SHOW I have already upgraded in SEPT 2020.0