Hi all
I started in the company I'm currently with on 20th March 2018.
My working week has always been 40 hours (including lunch of 30 mins to be taken at any time).
So for easy purposes, the hours were 6am to 2pm and 10am to 6pm, depending on the day.
We've been through a couple of managers/TLs in that time and they were the ones that set the schedules.
Today I received an email from my newest Manager (based in the US) that my day would now be 8.5 hours (including an unpaid lunch break).
So it'll be 6am to 2:30pm and 10am to 6:30pm
Original contract below:

Would I have a right to be miffed here with the change out of the blue? This is the third manager I've had within my time here, and none have said this at all.
Would I have any right to complain/refuse?
The company is going through a transition after purchasing another one, and in a couple of weeks I'll actually only be a team-of-one here in Ireland (and almost certainly will be done away with eventually), so (while maybe being a bit paranoid), they've really started pushing my buttons recently, and this is just another thing now.
Email today:
I want to make it clear that Support working hours in 'not-naming-city' should be 8 ½ hrs in the office with a ½ hour meal within the first 5 working hours. I understand the queue may be unattended for a half hour during your lunch. Please escalate any customer issues as a result directly to me. You have the flexibility to begin your shift a half hour earlier or a half hour later.