PaulC, it may have well been the case that the crew for the morning flights were not from the "nightshift" the day before. Infact very unlikely. However you need to undertand CAP371 which is the "flight time regs" etc for Aircrew. This is how an operator bases their code of conduct etc with its crews as depicted by the afformentioned manual and then approved by the CAA.
One of these requirements in a very broad sense - is that crew should not be called within their rest period prior to a checkin time. Indeed the crew need not be contactable during this time. Many crew including myself, have no problem with being told ahead of time if ops require a change of plan. However it is a legal right of the crew to not be told until their original report time. It only takes one crew member to not answer their phone and the whole plan is scuppered anyway.
As is the case with the pax - you can't please all the people all the time. Unfortunately in this case the regs take precedance.
At the end of the day as much as you felt hacked off and perhaps the crew should have been more open with you - seperate issue - I am sure you would rather have a rested and clear headed crew flying you home. That is why these rules are in place. Believe you me - if they (the airlines) could get away with it - christ they would have done it a million times by now as it saves MONEY and
PR for the airline.
The old saying "Being stuck between a rock and a hardpost" comes to mind!