Difficulty in resolving late payment fees

BUYER BEWARE: In February 2021 a debt collector very rudely told me there is an outstanding balance on my Spaces account (operated and managed by Regus). Regus made no attempt to inform me of an outstanding balance, all the while accruing exorbitant late payment fees.

How is it possible that Regus does not inform me via a call/sms early in 2019 that I owe them money? Was their plan to accrue late payment fees all along?

The debt collector wanted an amount of R2791.61.

I tried to resolve the situation by contacting the accounts helpdesk: I get told on 31 March 2021 that my online account shows all outstanding invoices and I pay the R3055.61 reflecting in the online account.

On 12 April 2021 the same debt collector informs me I also owe a further R249.01.

However, on 23 April 2021 another person at the account helpdesk informs me that some items in my online account statement are "internal accounting entries" and should be ignored and I actually owe a further R2880.01.

Why is it so difficult to permanently resolve this matter? The longer it takes the more late payment fees I will need to pay off course. Clearly I have shown that I want to resolve the matter by engaging the helpdesk and paying the amount outstanding on my account, but the matter remains unresolved.

Why can a senior accountant not just investigate to 1) see if I owe anything at all, since the accounting system is clearly broken and 2) issue me a full and final invoice to resolve the matter permanently.