Payment exceeding the agreed amount

I received an upgrade in October 2020 from Vodacom. The agent confirmed that my monthly upgrade fee will be R390. However to my surprise I'm being charged far more than what was confirmed by an agent. Vodacom says it's their agent called Like minds and they are unable to help me. They gave me the number *** which is ringig continuously. I have been a loyal vodacom customer for the past 16 years and this is the worst service I ever had