Blacklist of device

Worse company to take out a contract with, took out a contract device with them in January 2022 and my contract came to an end in January 2025, my device got ****** in February 2025 and I called them to blacklist my phone and they said they can not if I don't have an imei number as they can not pick up which device was being used with my number ear in mind this is their device which I took with them how come they don't have my contract documents, fine I found my contract ducuments which have the imei number called them again to have the device blacklist but they said its not allowing them to blacklist it as my device is now out of contract even though I now have the imei number that they wanted. Went to the store they also said they can not blacklist it. That time the person that ****** my phone has access to all my apps as device can not be blacklist. Keep receiving emails of verifications as they have access. At the store an mtn representative had the nerve to say I must do another upgrade while they can not assist with blocking my device. Never again