as much as you might dislike it however, the LFS is correct in this situation. That is way way way too many goldfish for a tank that size. That isn't just "a fish or two" that is really over stocked. I probably would have done the same as the employee, but then again I am a heartless SO*.
If I was you, I would ditch the goldfish (angel is fine, but would probably eat the neons and/or guppys, its hit or miss) and look at what fish you have remaining and decide if you want to keep them. Do be aware that Tiger Barbs are rather aggressive little fish and calm down a little when they get the chance to school (5 or more fish) and with only two, would probably take their agressions out on other tankmates.