I'l try to be as accurate as possible so others can get bthis deal.
I asked Orange for a MAC code as I was going to change to O2 (£7.50 a month for O2 mobile customers). As usual got passed around various people trying to put me off leaving, but eventually ended up with the Broadband Care Team. At this point I was offered my current package (which is equivalent to Orange Broadband Home Select Package, usually £20 a month) for £4.99 a month for 12 months. It is actually £9.99 a month but the first 6 months are free. Of course conditions do apply, you have to be outside of a current tied in contract and they won't provide a Livebox (as an existing customer you should already have one). If you are thinking of going to a cheaper package give them a call and ask what deal they can provide for you. Customer service number is 08700102462, for info my call was answered in 1 min 24 secs, which was about 7 mins less than Tiscali managed for a new customer enquiry!
I know people will say Orange are rubbish, Livebox doesn't work etc etc , but this is for existing customers not new business, so you will already know about Orange service. I have been with freeserve/Wanadoo/Orange for over 10 years and they haven't let me down yet!