The BT speed guarantee is just a gimmick. It only applies if BT can not get you back to your speeds after 30 days. It will be argued that your speed is Ok because it has not been a continuous drop in speed, just at peak times.
The small print on the BT web site:-
"Stay Fast Guarantee
We guarantee the speed to your hub. Check your speed using the MyBT app, online or by calling 0800 800 150. If after 30 days we can’t get you back to the speed we promised we’ll give you a £20 Reward Card. Up to four claims a year. Excludes outages, connection faults and home wiring outside of BT’s control."
Link about the guarantee:-
Hi @stomper1 I called earlier and sorry I missed you. The broadband team has been monitoring your connection over the last week and it is showing as always above 70mb at all times. How is your connection performing now and are you still experiencing a drop in the evenings?
it might say that my routers connected at that speed but its made no change what so ever,wish I stayed with ee now at least they offered 10 pound of each month,last time I spoke to bt c/s they more or less called me a liar
at the speed i should be able to get i should have trouble free internet but down loading a a file at 3.3mps my ping is all over the place
i notice since the clocks went forward my problem has also gone forward and now comes into place around 5pm i had a bt engineer booked for yesterday ,but guess what he never bothered to turn up ,so i lost another half a days work for nothing. Dose bt really want to find this fault cos this is the ideal time to find it even notice the fault coming even earlier then 5 pm