Unlimited Fibre Extra now capped to 67Mbit/s

[#1]

For anyone still on the Unlimited Fibre Extra package are you still getting your normal speeds? I've always got very close to the full 80/20 speed as the FTC box is right next to my house. Recently however I've noticed a speed drop. Checking it over several days shows the service is now capped at 67 Mbit/s, the same speed as BT's Social Broadband tariff. 

[#2]

Moderator's note:
Thread moved fromFull Fibre to Broadband.

[#3]

@Tench Have you checked for potential faults?

[#4]

Yes, nothing has changed. No faults, nothing running in the background on local PC or network. No IOT devices or phone updates. All checked.

[#5]

OK. Which router are you using, and do you still have a landline phone?