I'm putting this up as a sticky, because I've seen this question asked and the subject discussed a few times over the past week or so and that is
Can someone help me unlock my ECI modem? Upgrade your BT Openreach FTTC VDSL2 Modem ECI B-FOCuS V-2FUb/R Rev.B OpenWrt
If you post your modem, the seller will unlock your ECI modem and install
jsamuel's version of OpenWRT firmware.
£14.99 seems a fair price considering that includes return postage.
http://www.ebay.co.uk/itm/231887970610Link to seller--------
Note: Im not affiliated with the person nor can I make a personal recommendation, but it is a service some people are wanting, so putting a link up makes it easy to find in future. [Moderator edited to simplify the link to the service offered.]