First off, if you requested Flexi working then there would be a copy of this in your p-file, a file that yourself and your manager has access to. You do not need to submit a request you can simply ask to see it.
If you have been working a set shift pattern for a sustained period of time, then your manager, out of courtesy should give you 28 days notice of this change. If your rotas a created a month in advance, this is sufficient time to allow you to change personal plans.
If you work for a large enough company (and the way you are describing it, you do), then there will be policies in place for flexible working, time and attendance, and grievance procedure.....ask for copies, or check your employee handbook.
If you never completed paperwork for Flexi working and it was simply a conversation that was agreed, then the previous manager didn't follow procedure and therefore the new manager does not need to honour it, because for all he knows, you're pulling a fast one.
If you can, can you not see if a colleague can swap shifts/days with you for the times that you need?
If you feel that he is singling you out, or that he may be fobbing you off, raise a grievance in writing to his line manager stating what the problem is, what has happened and what outcome you would like, what's the point in bomb blasting irrelevant people into an email, you will only peeve those people off with something that can be dealt with by one other person not a whole load of unnecessary people. It doesn't add pressure to the manager, it adds unnecessarily wasted time to other people when there are procedures in place for things like this.
Take it from a manager that has had to deal with all sorts of issues like this over the years and have helped many front line teams and new managers with issues