I have an 06 R53 with a snipped wire to the post cat O2 sensor. The break in the wire is between the ECU and under the exhaust manifold. Does anyone know what wire to purchase for replacement? And where to get it from?

In case you are wondering how this happened, I took the car in to the repair shop because I lost all brake power. The copper brake tubes were in bad shape and at least one had failed. The specialist Euro garage here in town fixed the brakes but snipped the O2 sensor wire in the process. I took it back for them to fix twice without joy. I guess sometimes you just have to do it yourself.