BT - disconnected then reconnected giving slow connection

earlier this month my phone line and broadband stoped working.
an engineer visited to resolve and eventually found my line had been disconnected in the street cabinet !
he re connected my line to a new 'pair' and all started working again.
HOWEVER
previously my broadband ran at around 4Mb (yes thats right 4Mb)
it is now running around 2Mb
I was advised it will take 10- 14 days to retrain the line
20 days have passed still only 2MB
BT have now said not a problem as with in agreed levels

What can I do to get my 4Mb line back

Cross posting isn't allowed on this forum as it confuses people when multiple conversations are happening. You have already had a response in the other thread so would suggest the conversation continues over there.