I was off work on Tuesday, using up some leave. My out of office was on, everything was up to date etc
I heard an email come through around lunchtime so responded to it advised a customer I was not working today, and he was best to ring if it was urgent and gave the number
Wasn't anything specific, another staff member could handle it
Anyway he's complained about me, that I'm unprofessional and I should have rung him myself 
I don't work outside my hours or on leave but now I'm questioning myself if I should have rung him