I moved your post to start your own thread so replies will be about your problem and not confused with the originator of previous thread you may not be on same exchange
run btspeedtester and when first test completes then run diagnostic test and post results must be done with ethernet conenction and best with IE/Edge http://www.speedtest.btwholesale.com/
can you run when download ok and when you think there is a problem
can you post stats from your router
can you enter your phone number and post results remember delete number but leave exchange and cab http://dslchecker.bt.com/adsl/adslchecker.welcome
I gave your mobile number a quick call, I'm sorry I didn't get speaking to you today.
BT Wholesale have got back to me today to let me know they've moved you over to another SVLAN. This should improve the speeds you are seeing during peak time.
Please can you test your connection over the next few evening and let me know if you have noticed an improvement?