Most help desk software has a choice on labeling your request with a priority level. For a high priority, I expect some sort of response within a few hours. For lower priority requests, I expect to hear something within 48 hours. I think everyone has different expectations so only you can determine what is acceptable to you.
And that means exactly what? Should all their servers be offline and customer requests pouring in, I doubt replies would not lag behind. With no compensation mentioned, such claims are little more than sales talk.