Knock sensor 2005 r50

Hi everyone. Had the knock sensor replaced on my 2005 r50 recently. The fault returned the same day so the garage replaced it again and it’s been fine for about 3 weeks. (Although it hasn’t had many fast runs over 50 mph in that time.) Today the fault came back ( won’t rev over 50mph ish and really rough. Exactly the same symptoms as before). Altho I haven’t had the code read yet I’m betting that it will show up Knock sensor again as the symptoms are the same. Any ideas what might cause this to keep going or any other suggestions of what to look at? Cheers.