Invoiced and handed over for cancelled Phone Insurance

I canceled my phone contract, and Telkom employees gave me an email for the insurance to cancel the insurance, and I sent the cancellation email. However, Telkom continued to bill me for insurance.

I kept on complaining, but they kept on invoicing me. Because I refused to pay for the insurance I canceled, they handed me to the debt collector.

I wonder if insurance qualifies for handing over based on our credit regulations. Now I am expected to pay for their inefficiency

User's recommendation: They must write off that insurance bill