BT Broadband is from BT Retail who buy ADSL Max from BT Wholesale.
The connection between you and the exchange is owned and maintained by Openreach, who charge BT Wholesale for access to it.
Openreach are required by OfCom to provide exactly the same service to other wholesalers as they do to BT Wholesale.
BT Wholesale are required by OfCom to provide exactly the same ADSL Max service to all ISPs as they do to BT Retail.
So you would not get to be able to speak to the engineers any more than you can now. In my opinion you would more likely get a call centre in India with script-monkeys and even less chance of a useful support experience.
If you post your line stats from both lines in the Entanet or General Broadband Chatter forums here you might get some decent analysis of your problem. It sounds like typical IPSC or WBC inflexibility. You will probably find similar threads in the Entanet forum.
This comparison may interest you. Pity Feb and March are not showing, but you can see the Entanet drop in Jan. Not quite as bad as BT at that point.
What exchange are you on?
Edited by RobertoS (Wed 15-Apr-09 19:10:15)