MTN fails to respond to urgent network ***** case.

I have been the victim of a SIM cloning ***** where someone has been able to create an MTN SIM card with the same phone number as mine, and then use that device to make international calls, *****ing all my credit in the process. I reported this with urgency to MTN when I discovered it on Sunday and was told to phone back on Monday after 10am. I did, so and there was no progress, so I was told to phone back the next day, which I did, and of course no progress. The same situation has happened, today, Wednesday. Note that as my account has effectively been hijacked by a ********, I cannot load credit onto my phone as it will just be ****** in the same way. My phone is herefore unusable, and my MTN service useless. This would seem like a major customer service issue, requiring an urgent response, and yet as we can see, there has been no meaningful response. Hopefully someone senior at MTN will see this and respond before I go the full legal route to recover my money lost via MTN's poor network security.