I have had very poor connection over the past few weeks. What is the problem? These seems to be the same problem with most customers in my area - Gillian Avenue, St Albans.
Have you looked at Check service status at the top of the page? That usually gives a list of any known issues.You can also a run a test on your equipment from there.
If nothing is showing you could also try the Service Status number 0800 561 0061. This often gives details of more local issues down to postcode level.