There is a 10-day period after first connection of an ADSL line after installation. It should not cause poor performance.
In fact if there is poor performance in that period it is best to have it restarted after whatever is causing the slowness has been fixed.
See my
10-day training page.
It would be a good idea when you are there to find and post the line stats. It could just be a poor line.
See here for help. (That link is in
Useful links on my website as well so easy to find when you are there).
Depending on which ISP it is, as others have asked you, a the full results of a
BT Performance Test would be useful information.
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost.
Internet connection - O2 Standard.