Hi , I wonder if anyone can help , I brought an 08 Astra twin top 6 months ago , and  the horn stopped working more or less the min I brought it , then I had an issue with it not starting sometimes , and the controls on the steering gone a bit weird , so I did I little research and found that it is prob a cim problem as. Astra had been recalled for it years ago , anyway my question is if I got a cim from eBay , and a mechanic to fit it , does it have to be programmed to car and keys ? And would a normal mechanic be able to do this ? I did purchase a clip from Vauxhall that can be put in steering and may fox the issue but I have no faith in a piece of plastic if I’m honest and fear I need a whole cim - any advice would be most welcome 

I would be looking at the SRS clockspring as the culprit in this case as the information for the horn and steering wheel controls all run through this.
Either way, if you want to inspect or replace any components behind the steering wheel it is a job that needs to be tackled with care to avoid deploying the steering wheel airbag