In the 10 weeks I have been with BT (also an ex Plusnet customer).
I haven't used the online chat , but will do if my weekend drop in speed does not improve.
The BT Community forums are a complete and utter waste of time. I asked the same question, about my speed drop here and on the Community forum, I got an answer here and still waiting on the forum. The BT customer forums have a small team of Mods who are useless and seem to have a script to work from!