Bad Upgrade Experience

On Dec 2023 I app**** for a data sim contract upgrade online, they delivered a new sim card to me, activated a new line. I then assumed the old sim card won't work anymore. Put it away. Dec statement was normal. Jan 2024 statement came and I'm being charged for 2 contracts. They did not upgrade my old contract they just gave me a new one. I called they wanted me to pay R300 for cancelling the new contract AND pay for Jan invoice. They f*ck up and I must pay for it. Really disappointing how they handle their long loyal customer.