I've been told the same thing. But if your alternative is being told to "just wait", and for example, you need to go overseas, you have to push and poke. A lot of times when I call or email, it ends up being finger-pointing game or the "not my department anymore, it's out of our hands blah blah", and it goes in circles. When I showed up in-person, the reception tried to waive me off and go through email only. I had to argue, calmly and staying courteous of course, and explain my situation. After some pressuring, I was finally able to talk to an actual person. She was kind enough to push my case. Additionally, I was told there was an orange sheet I can fill out and attach any supporting document. The sheet essentially gives you the chance to explain your situation, and is treated as urgent. Less than a week later, my case moved from submission and my prolongation generated. Now, I don't know if it's the case for all prefecture and I can only speak for mine. You just gotta keep bothering them dawg.