Ex rejected my request for a week with the kids in the summer

My ex said he wont let me take the kids for a week. He knows its when my family gets together at some cabins. He doesn't like one of my cousins, and also likes to control me any way he can. My response was "Is this a precedent you really want to set? You were fine with 1 week on and 1 week off for spring break." No response. Our separation agreement says reasonable requests for vacation etc. won't be denied. Any suggestions for next steps? Im thinking maybe revising the parenting plan to be more specific regarding vacations like "each parent gets two weeks consecutively or separate between the last day of school and when it starts again"... but at this point i dont think he would agree to anything like that. Can it be forced through court? Is it something a lawyer would take on? Im in Canada. Thanks!