There's a lot of backstory but it's not overly relevant to this question.
DP has 2 young kids. In addition to other visitation, he gets them from 10am to 4pm on a Tuesday. His ex has started organising activities for them when they come back to her. This means that she texts every Monday evening saying that he/we can't do things because she's made plans for them after they come back to her. So over the past couple of months, he's been told not to take them to the park, swimming, the beach, McDonald's, softplay. Anything he's done the week, or weekend before, she books for the next week.
He's been going along with it, but it's starting to irritate him. So who is being unreasonable?