This happened about six years ago.
I'd taken redundancy from a previous job and decided to spend a while temping till I figured out what I wanted to do. So, I took a temp job working for the local authority. In my country, you have a legal amount of annual leave to take each year. As it was a temp job, I was accumulating my leave hourly, but it still had to be taken by the end of the agency's financial year. This was fine by me; I was working part time hours and taking some courses, using the redundancy pay to supplement my wages. It was chill, I had time to go to the gym, and I enjoyed the work; I even applied for a permanent post but it went to an existing employee.
A few months in, a colleague in another site badly broke her leg and I was asked to cover her job. Sure, I said. This was full time though, so I was working more hours, and therefore accumulating more leave. Aware that I would need to use it all by the end of March, I started making plans to use it.
I booked time off, they agreed, then asked me to work. And again. And again. By January, I accumulated, and I had one week booked off in Jan, one week in Feb to get decorating stuff done, and one in March.
We come back after the New Year, and… “Can you work?”
“I'll work, but I do need to use my leave; it's going to mean more time off in Feb/March, because I legally need to take this leave and can't get it paid instead”
“sure, sure”
February, and once again, they ask if I can work. I say yeah, except the Tuesday, which I need for the flooring fitters coming to do the hallway.
On the Monday; “you're working tomorrow, right?”
“no, I need it off for the flooring, so I can keep the cat out of the way”
“we really need you though”
The poor cat had to be put in a carrier for a few hours until the hallway flooring was done, as all the doors open on to the hallway and there was nowhere else to shut her in.
So I'm getting pissed off now, and I reiterate to the manager that if I don't use my leave, I'll essentially be working for free for three weeks and I'm not prepared to do that. I tell her that I now have three weeks to take in March and this is not negotiable any more.
On the 27th of Feb, I get an email.
“Can you work next week?”
I send a reply saying that no, I can't. I reiterate that we had this conversation two weeks ago, I'd stated that I would not be able to cancel any more leave until the end of the financial year, and I would not be in the following week.
Twenty minutes later, I get an email saying “thank you for your service, tomorrow will be your last day”. Not even a damn phone call.
Oh, and to add injury to insult, the staff member with the broken leg had bad osteoporosis and a pronounced hunch. I was told I wasn't allowed to adjust her chair while I was using it, so after several months of sitting in a chair adjusted specifically for someone with a deformed spine, I had back pain for months and had to see a doctor to get it sorted out. Bonus!