IB...... The timing and nature of the AGP means that it is very unlikely that crewing hours were the issue. Plus, if the flight was boarded, the crew were there and even with a severe delay, would still be in hours to operate. I am sure it was the ash but as with many pax, they like to think about sinister motives. Their probably was none.
As for the Menzies ground staff, I am not going to comment as clearly I wasn't there but as for hotels and vouchers.....................you only have to ask and explain your circumstances, they aren't mind readers. As for the Menzies manager, she is allowed a drink (and she was drinking it on the go.....i.e no break) and can you really say you know what her job entails?
Hope things get better for you soon.