MTN MESSED UP MY CONTRACT!!!!!

Everything with MTN on my two contracts has been great, First phone contract ending November 2025, second phone ending April 2025. Cool, installments up to date NOT A PAYMENT MISSED!!!! MTN SOMEHOW allowed an additional contract to my bill, Different person. Someone elses phone but my billed went from roughly R850 TO OVER R2000???!!!!! MTN has confirmed that this would be resolved immidietely so that i can pay my regular billl and move on with my life, i went into a branch, i tried to pay there and was told to rather WAIT FOR MY BILLING to be corrected and then pay. THIS IS NEGATIVELY IMPACTING ME AT THE CREDIT BUREAU all in one month??? MTN, PLEASE CAN I PAY MY BILL AND PLEASE CAN YOU FIX MY ACCOUNT!!!! THIS IS UNNACCEPTABLE AND NO ONE AT YOUR CENTRES OR CALL CENTRES CAN DO ANYTHING BUT ESCALATE THE MATTER.