I understand that legally only a 20 minute continuous break is required, so you should at least insist on that.
Unfortunately I think it's becoming common now for breaks to be taken up by work, and it's also common for people to work longer than their contracted hours. When I was a teacher, for example, I had a 30 minute lunch break but by the time I had kept behind pupils for short detentions and tidied up the room, and dealt with queries from kids in the corridors, it was time to set up the room for the next lesson.
I suggest you go out for a walk for maybe 30 minutes.
You can press the point and demand 90 minutes over the day but it may not lead to good relationships and may just make things harder for colleagues, so ultimately to may be better accepting things or moving on.