Penalties charged for cancellation of an expired contract

I requested a cancellation of a data contract which expired on 31/01/2024 I received the instruction on 23/01/2024 and confirmation that the number was converted to pre-paid was received on 29/02/2024. How ever, they billed me for February again on 01/02/2024. I stopped my debit order and only paid the remaining due balance. I contacted them again in February to query the charges and confirmation was received that the contract will be converted to pre-paid, which means this was not done as per their email received in January. In March the charged me penalties for an early cancellation, but the quote was send to me in January with a R0.00 amount penalty. I was informed yesterday that they have blocked all of my numbers due to non payment of a cancellation done in January.