MTN over billing customers

I am a loyal MTN customer & had only good service from them but after my last upgrade done this year 2023 it's been very rocky. My upgrade was done @ the Chatsworth Centre branch with Felecia Singh & these are business contracts. Upgrade was done in September & I have been over charged ever since the upgrade. I have visited the store many times but somehow these guys can never get it sorted out or keep moving the blame around. It very frustrating that I can't get updates from Felecia Singh when she promises to get back to me & I even have them on whatsup but that also doesn't help. The only other move I can make is to stop the debit order but that in turn will hurt my business. It's a no win with MTN & all I ask is do the right thing with loyal customers & if you'll made a mistake correct it. Stop acting like your customers don't exist. Please get your Chatsworth Centre Branch in order or your customers will disappear.