I don’t know what the prioritization is if you are e.g. explicitly registered in some Google database, but I’ve had a good experience with just marking up the opening hours (addresses, etc.) with RDFa (or Microformats or whatever else Google accepts these days) on the official website. Of course how easy it is depends on the number of layers between you and the actual HTML, and my case was rather straightforward (three locations with separately listed addresses and opening hours), but you might want to check if it’ll take some of the pain out of the process.