Request for handset unblocking

I had requested MTN to blacklist one of my contract phone which was lost, but the blacklisted the wrong phone I emailed them and called them that they had blacklisted the wrong handset they asked to email the an affidavit, proof of purchase and my I.D copy on which I did and they later told me that I must switch off the device and the sim card must be removed and I must wait for 72hrs before i switch it on again after the 72hrs expired when I switched it on and insert the sim card the phone still has not network, I called them informing them that the phone still has no network but they told that the un-blacklisting was successful. I again called them to inform them that the handset is still has no network they ask to take the hand set to the store which I purchase it so that the Technician on store will attend to it but he refused citing that he only works with the repairs not the network everytime when I called the MTN a consultent needs the same information but I get no help it almost close to three months without making or receiving calls through my device I feed up with the whole situation I need them to restore the network back asap.