Mtn Contracts

I was owing 4195 for my cellphone contract and paid an amount of R1200 in store before they handed over my account to Nudebt to my surprise they never allocated the payment i made in store before the account hand over. MTN gave them a wrong amount as anoverdue to my account made payments as follows08/08/2024 R700 & 04/10/2024 R500 in total R1200 (Nudebt says they dont have this payment as MTN only gave them this figure R4195) and suddenly i owe 5900 like really? Please fix this error