R15K LISTED ON MY NAME NEGLIGENTLY!!!!

Mtn i am actually at my wits end with your company its been 3 months of constant back and forth and one sided communication from ME as i have to email and call at my expense with no resolution. i am an active contract customer and decided to take out an additional device in Oct 2023 which i returned SEALED 4 days later filled out the relevant paperwork and was assured that i wouldn't incur any additional costs and that i followed the correct process a month later i follow up as i received an invoice for this device that i no longer had to then find out that the cancellation wasn't processed December comes same issue as the cancellation was only processed much later on long story short as it stands today the device was never active and was returned but the total cost of this device is now listed on my name this is despicable as my credit profile affordability is now affected by at the hands of MTN you have NO SHAME!!! i was told that the legal team is to assist me to this day NOBODY assisted me i have emailed the legal department numerous times to get a paid up letter as i need this R15k OFF MY NAME !!!! I DO NOT HAVE THIS PHONE AND THIS IS AFFECTING MY LIFE NEGATIVELY!!!WHY HAVE YOU DONE THIS? when i call you i get a different story every time and i am sick and tired of dealing with this matter as it is now worse!! because of mtn i cant apply for anything at all! i am stressed out and disgusted by the lack of communication and unprofessionalism and NEGLECT !!! its been 3 months and i will take the legal steps i need because I'm getting NO HELP!