Old ADSL exchange - full up maybe

Our local exchange handles about 150-200 properties and is only ADSL Max. Recently most of us have been seeing a slowdown of dowload speeds in the evenings, which never occured say 3 or 4 years ago. Our current thoughts about this are:-

a) There has been a small number of additional houses been built in the last few years
b) There has been a very large increase in the number of holiday lets and tourists to stay in them
c) More people of using streaming services.

I'd appreciate any other thoughts on possible causes but also how do the slow speeds stand up against BT or whoevers claim about speed range. Contracts typically say 3 - 6Mbps, although some further from the exchange get less than 2 - but evening times some of us occassionally see less than 3 when during the day we're usually get over 6.

Can BT or whoever be held to account if the evening speeds drop below the contracted rate - note this is not due to deliberate throttling we believe?

Who is your provider?

Streaming and smart TVs sound likely culprits to me. Possibly insufficient capacity on the SVLANs at the exchange.

Are you perhaps on the plans for FTTP, like huge chunks of Cornwall, so they won�t be investing at your exchange? FTTP would come from a bigger exchange further away.

If the old IPStream service is the only option then its known for having poorer performance in the evenings, so if lots of heavy users have appeared then you may see slow downs.

Which exchange are you talking about?

Apologies for the delayed reply. I thought I'd post it but it seemed to go missing. However.....

My ISP is John Lewis which is really Plusnet which as you know is part of BT. My friends who are experiencing the same problems are all BT direct.

The exchange is here https://availability.samknows.com/broadband/exchange...

If I run the BTW speedtest I can get 6.5 during the day but the further diagnostics puts up this statement:-

Acceptable range of speeds (Mbps) - This is the speed range that we believe is acceptable for your broadband circuit and is measured in Mega-bits per second (Mbps). If your download throughput speed lies in this range there is no fault on your line and your broadband service is deemed to be working OK.

and the range I get is between 0.6 to 7.15Mbps - sufficient range to give BT a get out in most cases despite giving you the impression that your contract bottom speed will be 3Mbps.. I guess there will be many weasel words why they can break the contracted speed.