Caledonian

Anybody got any ideas on a tax investigation that is running round in circles? Over 2 years now and getting nowhere, same old stuff rephrased. He is hellbent on finding something, bad/good news is there's nothing to find. How long can I expect this to go on? Or do I just admit to the next thing he queries to make it go away? I know that seems like a crazy option but it really gettingb to me now!
TIA
C