Vumatel Billing errors

I logged a fault with my fiber line which was an existing installation at the premises I moved into which eventually required a technician to resolve at the premises. However, for the last month and after numerous mails and calls to Vumatel accounts, I am still receiving reminders and follow ups for payment of a fiber installation. The accounts response id that they will investigate further. How difficult is it to see that a fault and an installation are two completely different items.