Transunion refusing to assist

I have a dispute TU*** , Mix Telematics billed me incorrectly and they are willing to help. Their credit manager availed herself because for some reasons they couldn't locate emails from Transunion. She sent the bellow email:

Good Day TransUnion Team Kindly assist to update the client’s profile as his account was not overdue. He paid a settlement fee on the 26th January 2021 and subsequently the billing for February 2021 months subscriptions was done. We have issued a credit note from Mix Telematics to rectify the error. Please update the client records. Regards Nirvashnee Atchiah Credit Manager (Africa) <image001.png> t. +***2 e. *** www.mixtelematics.com

Transunion agents are refusing to help, all that Nirvashnee is say is that she needs to speak with Transunion investigators to resolve the issue.