Do a Partial Water Change (PWC) of 50% to get your Ammonia below 0.25. The goal would be to ideally test 2x (or more) a day and to keep your Ammonia and NirtItes below 0.25. FYI - Levels above this can be deadly over time, but regardless they all have perminent damaging effects (if kept under 0.25, these effects are 'tolerable' in most hardy fish).
Yes reading the numbers are tough, but error on the side of caution, and you will do okay. Keep the water the same relative temp and add de-chlorintaor too
Also, the more you feed the more you will pollute and have the potential for more ammonia spikes. Do gravel vacs during each PWC too.
Lastly, no more fish until your cycle is finished. I can't tell you how disapointed I am in your LFS right now :steam:
The advice from the other posters is good. Just keep up with your PWCs to keep your water parameters within tolerable levels for your fish. If you don't already have one, get a good test kit (I prefer the API liquid kit myself). You have some sensitive fish in there that will be hard pressed to survive very well through a cycle-process.
I agree with Sammie, contact your LFS and see if they will accept any of them back

This can only help. The 80G tank will help obviously, but again it will take time to cycle that as well.