I was suffering the same low peak time speeds as you are Dee....but i decided to be a pain in the ass to BT and it now my speed sits consistantly, throught the day, at between 3-4 Meg.
At the very least Dee, I would go to your ISP and argue the case that technically, you are paying for a broadband service that isnt being provided. Thats the angle I would go for....coz if nothing else....it may well lead to a sizebale reduction in your broadband bill....just as it did for me. I got double bubble tho....as my speed issues were also rectified to the level they now are and I am paying ?10 less than I should be. On the other hand....im not quite sure what i was doing paying the over inflated price of ?25 per month in the first place!