Not being billed for months after reporting it twice

I have been paying my fiber account every month without fail, only after moving it from Bloemfontein to Durban to see they haven't billed me for 2 months so as a good client I phoned and told them listen please amend and bill me the agent confirmed it has been sorted and I went on paying. Yesterday I received the invoice again and actually looked at it to see my account to be in a negative R10 000, I phoned and an agent explained they haven't completed my order for the relocation and hence they haven't been charging me since April 2023. Take note I have phoned a couple of times to ask for an email adress to be changed for an adress change and even to query the speed of the wifi and no one ever picked this up even after I logged it. As a client it was not my job to tell Vodacom how to do theirs. Now the best of it all they want to back date the invoices but the order wasn't completed so isn't it fair that the month the order is completed the billing should start? I am very sorry but this is unacceptable since this is the second time I had to call about this. This is money we are talking about and I feel since I did my part this money should either be refunded or be left on account until used up from October 2024 until when the account is back to R0, but back dating the invoices after I had to ask you twice to "take my money" is unprofessional.