Still invoicing me for contract canceled 4 months ago

I tried cancelling my contract with MTN since July 2021 but no one answers their phones or responds to email. Eventually a lady assisted and an amount was owing, which i had to pay before they could cancel. The amount was paid and the contract was cancelled and the number was migrated to a new provider. Yet they keep sending me statements i have emailed everyone possible with POP and still no response. Absolutely terrible service