Neglected by Telkom

I was in a process of buying a car and the bank rejected me because they say there is an account i did not pay. I asked to send me details of that account. And telkom pop out that they went on debit on 24th while pay day is on 25th. Now when credit check is done that bounced debit blocks me to anything. I can not buy a house or car due to that debit they tried on the 24th. I went to Telkom shop in Vincent to request a letter that state that my debits are on the 25th and state that i was never on Arrears with them. (06th of November 2018) they took my number and said Pretoria people will assist me. They call and promised to assist me urgently. I have called them 3 times sent them messages on twitter. I went back to Telkom shop in Vincent more than 3 times and up until today i have not recieved the letter im looking for. Now i dont know what to do any more because my life is blocked. I needed to have a car before the 25th of November. But it seems like my life is ruined and Telkom does not take our matters seriously. What i want to know from Telkom is why it takes so long to draft a letter and fail to deliver to their promise of supplying me the letter within seven days