Audi S5 query

[Rosanne58]

Hi, I’m now on my 4th Audi having had 3 different RS models previously. This is an S5. We very quickly discovered it had an oil into coolant leak and although the car is with a specialist Audi workshop they have trouble in obtaining the parts necessary to remedy this fault.
Is this a known problem for any Audi model of this type (B8), as the repairer is unable to obtain the necessary parts?
Is it worth my trying to help him by contacting additional suppliers?
if I do this I’ll need details of the part(s) in question.
Can anyone supply any information at all that might be helpful to me?
TIA