Mweb is ****ming and terminate contract if you 5 days late

I got Mweb Fibre in middle November 2024. I got billed over R700 at the beginning of December I paid the amount 5days later. Then They canceled the contract and now they want over R2700 from me for canceling fee coz I was 5 days late and my bill must be R300. So Mweb is ****ming people out off money coz they terminated the contract and not me.