HOW DO I BLACKLIST MY ****** PHONE

For the past 5 days I have been trying to blacklist my ****** phone so that I can claim from the Insurance, but it seems like its an impossible mission to do so on MTN, the dealers are saying they don't have a system to blacklist and that I should contact the call center, I have been spending at least 2 hrs everyday on the phone but no one is taking my calls. the call center is useless and this is very frustrating.<br> <br> now my question is how do I blacklist the phone, please help I need to get this phone blacklisted asap.