IMEI Issue

Hi, this is so frustrating that your mtn consultant cannot assist me with my query. I lost my phone. Phone details samsung SM-A042F, i had this mtn sim card in it ****when i called in to black list this device using this IMEI ******, ****i was told they can't pick up this IMEI numbers they used my personal details to verify me and they have successful blacklisted the phone. Now insurance is demanding an explanation from MTN as to why they can't pick up this IMEI. They need something in writing. My claim is on hold due to this. Since Monday I have been calling no one who is willing to assist me