I believe that that has been an inherent problem with the brake/ looms. The year of my R8 is 2020. I had a problem with the brake light and the garage replaced a full set of looms as they said they were rusty. I presumed that these were plastic coated. The light was still on so they then replaced another part. I cannot remember which part this was. Have other owners had this problem.

Why on earth would the copper wiring looms on a 2020 R8 be rusty? Even the connectors have 3 o-rings to prevent water ingress.  

Maybe if the connector was somehow broken, water could have corroded the contacts, but you wouldn't need a new loom to fix that.  Even if the PCV coating wore off somehow you could easily just replace the affected wiring, not the whole loom. 

Unless you mean they replaced a short piece of wiring loom/ connector associated with the lights. More details would be needed.  

See a lot of Ignition coil issues on these but not brake light wiring... 

Thank you, I have to admit it's not my car it belongs to my son. I am just trying to help as I believe that the garage are .... ! and other unmentionable words. 

Hello Jean,

Regrettably, don’t think you are giving us enough in-depth detail to be able to comment. 
I would strongly suggest that if your son is dissatisfied with the service he is getting, then it would be in his best interest to find another recommended garage. 
Kind regards,

Gareth. 

Thanks Gareth, (my son's name ) points noted. I will post a more detailed account if needed, but the other post I found very helpful.

Did they do a diagnostic check to see if any fault codes flagged up?