Terrible service!!!!!

My sister has a big problem with MTN, she has been put on the credit bureau for an amount of R 1683, however she has 3 contracts with MTN, which are all active and up to date. She is currently busy with a home loan application, but it cannot be approved due to this amount from MTN. She has contacted MTN numerous times via phone as well email, but she only received an email from Andre Bowden, where the attachment is only blank. She needs this to be sorted out urgently, she has been a loyal customer of MTN for 30 years. How do you put someone on the credit bureau and then cannot provide any details as to why? The call centre agents are not helpful at all and Andre Bowden has gone AWOL! What kind of service is this from you MTN!!!! Contact my sister on *** urgently!!!!!