Transfer of Fibre line to Vodacom is likely to interrupt my job critical Internet connectivity

Vodacom is the infrastructure provider for Fibre in my area. I am currently with an alternate ISP for Fibre internet (Vox) and want to move across to Vodacom to reduce the communication chain length when there are outages. Internet connectivity is critical for me and I want to ensure that there is a seamless transition from the old ISP to Vodacom. I have cancelled my line with Vox and received an associated cancellation of the line from Vodacom. I app**** for a Fibre line with Vodacom and received email confirmation and an order reference number a week ago. On 18/10/21 at approximately 13:00 I phoned the help line *** to determine status of the order and was not able to get any coherent feedback. It appears that because my line is still active with the old ISP, that no action can take place on establishment of Vodacom as the new ISP until the finalisation of the cancellation of this line. The Fibre help desk was unable to perform any form of check on the Fibre Order number that I had received, as the order process needs to proceed further before they can assist. The Fibre help desk advised that only once the existing service is cancelled, can the new one be initiated, which is likely going to leave me without Internet for a period (which is what I am trying to avoid). The help desk gave me vague assurances that it would be a seamless transfer, but based on the fact that they are unable to trace my new order in the system at all, this is not likely to be the case. Please could someone with an elevated view of the processes of switching between ISP's on a Vodacom fibre line review my account and provide me with detail of what steps are outstanding in order to ensure that I do not have an interruption of my connection?