Ugh, that's the worst feeling. So they basically sold you a list of things most people figure out by just talking to others? What really gets me is the price tag for that. Did the sales page make it sound like some secret method, or was it just vague promises?

I had to bend my latch twice before it finally sealed right.

That guy is gonna cost someone a big repair bill. On the newer stuff, you absolutely have to flush out the old coolant completely or the additives fall out and turn to sand. Seen it plug up oil coolers and kill engines. Always use the cleaner and follow it with a thorough reverse flush.