profile schmofile. dslam, blah blah, speed shaping/ trimming, transit/ peering.. all bollox
sounds like you have an issue with your line, mol.
plug a normal wired phone into the test port on the NTE (ALL your other kit disconnected) and listen for crackling/ buzzing. do you have any recent examples of your phone ringing but no-one there? rings once and stops? crossed lines? people trying to call but cant get through?
tried swapping filters and the lead from socket to router? is your house fed via a pole outside or underground? if overhead,what colour is the wire to your house?
slow speed can be the result of a line fault.. the exchange kit is talking to your router but is having trouble being heard.. so it slows down in order that the data can get through.. a bit like trying to talk to your deaf granny.. slow and steady.
once the problem is cleared, the exchange kit will eventually see that the line is better and will jack up the speed to suit.
resetting the speed without fixing the issue will not work in the long run.
speedtester is crap. will not help you resolve your issue.
the phone network is a living thing. it is constantly under attack from the elements and other factors. if you had 2.5meg before and it has got slower, the elements or some other factor is affecting it and can be fixed.