It could be that your line or a connector has deteriorated overtime or there was noise or a fault on your line that caused it to drop. It might still improve but even if it doesn't I would imagine that BT will not do anything to assist in getting you back 5.67Mbps when you are still within your estimated speed band.
To get the best possible sync rate it's worth during the modem swap during the day, around lunchtime. Personally I would try just powering off the existing modem for 30 minutes and powering it back on.
Your IP Profile is determined by how well the modem syncs with the cabinet, so if you do it during the day you'll get a better sync than at night or in the early hours of the morning.
Folks, apologies for the delay in getting back to you. Finally managed to hook up the HH5 - here are the stats:
Can anyone advise whether these are good / bad? Whether there's scope for improvement?
|6. Data rate:||19999 / 76405|
|7. Maximum data rate:||25537 / 76904|
|8. Noise margin:||15.3 / 6.6|
|9. Line attenuation:||0.0 / 9.4|
|10. Signal attenuation:||0.0 / 9.4|