Thumb sucking billing by Telkom

Telkom is really messing things up for their customers, last month I paid Telkom an amount of R4246,87 which was for December and it’s for the spend limit I used whereas their spend limit is only R500 but fine I paid it. Now Telkom has billed me R6169,87 for last month whereas the initial amount is R1813,07 that I have to pay. Telkom must remove the R6169,87 as it is hindering my chances of getting approved for my home loan. Thanks.