Really glad to hear that tech support was able to help you. It would be super helpful if you could tell us if they had to do something on their end (and that the did it!) or if they walked you through the "usual" steps - uninstall/reinstall, run SimCityRepair.exe, etc. I would have probably suggested you wait, it does take some time and sometimes a city has to run to catch up in "Sim time" a bit with the rest of the region.
So now you have a city that won't load? Does it give you an error message like "unable to load this city at this time" or just hangs?