Take responsibility when it's your error

My cellphone could not pick up network. I am with Vodacom and it was determined that it was on fact MTN who had now blacklisted/blocked my phone. On entering discussion with 3 managers at the century city customer service centre I was told there was little they could do but would contact someone and get back to me. This didn't happen and it requires another visit to the centre. You cannot get through on their contact number, no-one ever picks up. After much argument someone took responsibility for attending to the issue but this proved less than helpful. To date, I still cannot use my handset which MTN has incorrectly blocked and have now been told that I should return to the store I received it as there is nothing more they can do!! The general attitude, lack of feedback or urgency in attending to customer is appalling. I have had to phone regularly just to get feedback which has been less than productive to say the least. MTN, you blocked the wrong phone due to someone's error inputting the incorrect IMEI number. It's your fault, fix it!!!