I am sorry to hear about your frustrations and the project not going as well as expected. I had a look at the instructions they post
http://www.homedepot.com/catalog/pdfImages/24/24526326-a562-4c82-9255-95dafe9e6fb2.pdf and I can certainly understand your frustration.
When we sell our
metallic floor epoxy systems we tried to assemble a more complete kit based on what we have seen.
We can't include repair materials (in the basic kit), because we have no idea how bad someones floor is and what all needs to be repaired. Prep is always important but with metallic systems, repairing and prepping the floor is key.
We do include a black primer, because a prime coat with metallic systems is essential. The black in particular really highlights the metallic features. After the floor is primed, we include a high build epoxy and pigments. The higher build epoxy does a nice(er) job of hiding flaws in the surface below.
One the floor is primed and coated, we include a great clear coat with an anti wear / anti skid built in.
So why am I talking about all the stuff 'we' include? Because the bottom line, for a good metallic system, you have to do it that way. On some older floors we end up using two primer coats.
So as you go back and try and improve this floor, I would highly suggest a multi-part, high build system as it is going to give you the results you want. The best bet may just be to grind the floor down and start fresh.