I'd say its either

1. A line fault causing low speed syncs

OR

2. Moved onto 21CN WBC (ADSL2+) and after a few days a banded profile has been applied limiting speeds.

The later can be reconfigured by ISP support, the former will require engineer visits to assess, report, visit, try to fix, report, visit again and possibly fix.

In reply to a post by hussnainh8:

Does having 3 phone lines in the house affect the speed by any chance? I have one connected to the main socket near my computer. another connected underneath the stairs and another in my room. Does this affect the speed?

I think folks would have automatically assumed all the phones were filtered and would have concentrated on ADSL issues.

Was the phone that you disconnected unfiltered?

Three telephones that are working properly and correctly connected and filtered should not be an issue.

I don't understand what you mean when you say "the other phone isnt connected to the socket but I can still recieve/make calls through it" - do you mean that this other telephone is a cordless DECT handset?

Properly filtered phones should not affect the BB.

How many sockets in house and which ones (master or slave) are phones connected to? Are any phones cordless? In which case only the base station counts.

If removing 1 phone corrected problem, then it was either unfiltered or faulty.

In reply to a post by hussnainh8:

I have finally fixed the issue. Like I said I had 3 landline phones connected in the same house and because there where 2 phones connected to 1 socket each this caused my download speed to go down. Now my speed is running at atleast 6mbps which is fantastic. I did ask earlier if having 3 landline phones connected would be an issue but no one bothered to reply to that. I took 1 phone of which was connected to the socket and my speed is all back now. I have 1 phone connected to the socket and the other phone isnt connected to the socket but I can still recieve/make calls through it. As they are both the same phones.

Now with modern digital telephones only wire connections 2 and 5 are required, 3 is for the old electro/mechanical telephone bell wire connection and can cause interference with broadband, the number 3 wire should be disconnected at NTE5 master socket.

UK Telephone wiring information to help you.

http://www.telephonesuk.co.uk/wiring_info.htm

http://www.wppltd.demon.co.uk/WPP/Wiring/UK_telephon...

http://www.rob-r.co.uk/other/UKphonecatwiring.htm