LLU (Local Loop Unbundling) has just been explained by others.
Going to BT would not help, as it does not cut out the middleman any more.
The LLU suppliers have their own equipment on the exchange end of your line. All other ISPs - Newnet, Enta re-sellers, IDNet, Orange (in your case) etc come through the BT DSLAM/MSAN. This is owned and maintained/managed by BT Openreach.
BT Wholesale sell the access/use of this equipment to the ISPs, and provide the actual connection to the "BT backbone" - the main link to the rest of the net. The product BT Wholesale sells is IPStream (and Datastream which some ISPs use).
The ISPs above buy IPStream from BT Wholesale - and BT Retail that you would buy from are just another ISP for that purpose. It could even be worse for you, as this structure is set up to comply with OfClot's requirement that all ISPs must have equal access to IPStream to sell to you. As a result, Wholesale and Openreach have to bend over backwards to show they are not favouring Retail, so Retail may find it harder to get results than external ISPs. Your line fault is Openreach's responsibility to fix.
Even with LLU the line from the exchange to you is Openreach - even if you pay the ISP for it not BT Retail.
Fun isn't it?
PS - Newnet tech support is excellent.
Waitrose Broadband is supplied by Brightview - whose main ISP is Madasafish. Brightview has just been bought by BT.