Contacted HM to replace shower valve on a Friday, and scheduled an appointment for the following Monday. They charge $80/hr., plus $40 per service call. The total cost for a single hour, though not cheap, given the nature of the job, was less than a per job quote I received over the phone from another plumber; so, I went with it. The job was completed in about 40 minutes, so Jack asked if there were other work items around the house that could be addressed in the remaining 20 minutes. The valve that was replaced has been in for about a month now, with no apparent problems.