Depends on the company size too. A small hosting company might prefer to concentrate the limited manpower on solving the issue rather than answer the tens or hundreds of "update on what's happening" requests. I do think that a general informational response should be given within a couple of hours, so as not to keep the customers in the dark for too long, when the issue takes a while to be solved. I consider that a trade off that one must be ready for when desiring the personal touch of a small host.
With a bigger sized company, response times should not be affected much.
The resolution time will depend on the issue. It can take quite a bit of time, as not all causes of problems are easy to pinpoint.
Is there a forum where one can pour his frustration with non-performing reseller?