Pathetic Service from Transunion Credit Bureau's "support center"

I have settled an account on 10 September 2020. Unfortunately, this payment has never been updated as paid up. After numerous attempts to get someone at Transunion to assist me, I'm not getting anywhere. Their support center (not sure why they call it that, as it most definitely does not give you any support. . . .) is not interested in assisting WITHIN their mandated timeframes.

They CHOSE to wait a FULL 20 working days or whatever the timeframe is, before they update statuses.

I have spoken to "support agents" and they confirmed that they have the relevant documentation and paid-up letter to address a dispute I have, BUT I have to wait the full 20 days, before being assisted. As it is, their systems are at least 3 months behind!!

How any financial institution can use data from Transunion to make accurate decisions, goes above me. . . . .

In the mean time, I being inconvenienced, due to their incompetence and lack of urgency. We have lost a house we wanted to buy, with the main reason being that our credit profiles are not up to date.