Liers and not willing to assist

I had a data contract with Cell C ending Nov 2023 and was looking into getting a new phone in September. The agent assisting me told me the new contract would only take effect in December after the data contract had expired. I got my last data on the 1st and on the 12th, the new contract came into effect. All my data for the month was gone and I was given 2 gb on the new contract. I called in and was told unfortunately that's how it is and they can't help me but I'll still be billed for the whole month! I only used that data until the 11th and it's now gone but I'll be billed for the whole 50gb? No one is willing to help me or give a resolution! Agents lie when looking to make a sale!!!!