Sounds like Indian bloke followed his script-his computer told him to send new homehub and in the meantime tier 2 realised your router config needed changing and did so.
I'm with SKy now but with BT, I found the best way to get a customer service issue escalated to next level - (English person on phone with ability to tweak) was to baffle them with science - cite throughput speeds, attenuation levels and connection speeds. It throws them off track and they will pass you up the line.
If you don't do that they expect you to do the rigmarole of switching filters, plugging into master socket etc etc. Just cut to the chase, tell them you have done all that and throw some science at them.
Beware though: I'm convinced that BT have some sortof "sinbin" whereby your number is recognised and you will be either put on perpetual hold or disconnected when speaking to them.
I have crossed swords with the feckers several times.