Give Linkqage a call. They are one of the better TP-Link partners and distributor in SA. According to the TP-Link website it is a new device. Maybe stock is an issue.
Delays are to be expected for this time of year. All the FNO's entered a freeze period during December and January. No new clients were added to the networks during that time which is causing some delays.
ONT's are usually locked down with only the FNO being able to access it. If it has been reset, that would have wiped their settings which allows them to remotely connect to configure it for the ISP service.
Its rare that you find more than 1 FNO in the same street or complex. Your best would be to use the coverage checker on Openserve's website to register interest.
No ISP can guarantee speeds via Wi-Fi as it operates on a shared spectrum with only 11 legal channels to use on 2.4Ghz. Just switch the channel or get a Unify access point to handle your Wi-Fi connection.