Did you get the free upgrade on your previous contract and now lost it by renewing? I'm only guessing to be honest but that's a hell of a drop.
Just renewed my contract and almost immediately had a 50 % reduction in speed. Our broadband has been very steady this last year , seems like to much of a coincidence.
Is your phone line working, can you get dial tone, and is the line clear without any noise?
post the stats from your hub if hh6 then advanced settings then technical log information
enter phone number and post results remember delete number https://www.btwholesale.com/includes/adsl/main.html
what about posting stats
Sorry I am using a Billion router as the BT HH could never hold a stable connection for me. The connection has improved from under 6 to 9 but last week I had 12.
when you renewed the package connection looks like reset and you lost G.INP. just manintain connection and DLM will activate G.INP and this will drop noise margin to about 3db and give a bit more conenction speed could take 10/14 days provided line stable and few errors