E70 heated seats

[Big Ste]

Can anyone help please, my front seat covers were replaced under warranty and now have the heated elements. I have purchased the controller with the heated seat function and fitted it. There seems not to be any where to connect the heated element into under the seat and I think some wiring is missing from the reat fuse box. BMW have checked and informed me there is:
1. only 1 loom for all E70's
2. there is no additional wiring available
3. The seat's will need coding in

i fully understand that this may be a long process, but I'm not changing the vehicle and am happy to make up some wiring. There must be something on the open market for coding etc or only main dealers will be able to work on modern vehicles.

Help please anyone.