I haven't really looked around in this space but I've used zendesk which 1) sucked, and 2) once you ignore all the useless javascript effects, it didn't really

I haven't really looked around in this space but I've used zendesk which 1) sucked, and 2) once you ignore all the useless javascript effects, it didn't really seem to do much. WHCMS is simpler and better but I've only used that from the customer side. So I'd expect there are a zillion FOSS systems out there that perform this function, and if none are to your liking it's always possible to modify an existing one. Why write from scratch? Am I missing something? This seems like something that would have been done on one of those screen builder apps in the old MS-DOS era. The drupal repository might be a good place to look for this sort of thing.