Loan Application Gone South Thanks To Vodacom

I had an outstanding amount on an account from a few years ago with Vodacom (approximately R500). It was brought to my attention for the first time when trying to get a loan to purchase a house. I am currently getting declined by all banks because Vodacom never ever informed me of this outstanding amount. I paid the amount outstanding about 3 weeks ago, but have not received any proof of this as of yet. I need a letter to send to the banks so that I can apply for the loan otherwise we will lose the house. Please can this be sorted out asap.

I tried calling legal department when I was still in South Africa, but no help as they couldn't provide me with the letter I needed at that time. I am currently working in Turkey and cannot call the legal department.

Please help.