Bad service and employees not doing their jobs

I have a problem with my February 2021 invoice I'm being charged a migration fee of R2384.03 they say it's an early upgrade but Mondo says this was a normal upgrade I even got a notification from MTN that I was due for an upgrade.

I've addressed this issue with MTN several times no one seems assist me in this matter I'm being transferred all departments with no help. If this issue is not resolved I'm willing to take this further because I think they should be transparent with everything to us when we apply because I wasn't made aware of this migration fee before so why should I pay for something I don't know of and this is not my first upgrade with MTN, and I've been a loyal customer for MTN for the past 10 years and this is the treatment I get?

My query reference number: ***

This is an sms from Mondo below confirming that this issue should be addressed by MTN,

Good day,

Trust you are well Kindly note we unable to assist with billing on our department please contact Mtn direct on *** to assist .

Kind regards, Mondo Team

Please assist me in this matter above your assistance will be highly appreciated

Regards; Tshepo L. Letsoenyo Cell Number: ***