Sounds like Busch Gardens did the right thing!
They offered you tickets to come back to prove to you that you experience was an unusual one, and to try to make your next experience right. If these were your third and fourth visits chances are, in their minds, you'll be coming back. Free tickets for these days are your refund for these days. You can't honestly expect them to refund you for previous visits as well. You just chose not to accept it, your fault. If you decide to take this to an attorney over a couple hundred dollars they will most likely laugh at you, and gladly take your money.
I can guarantee you that they have paid a firm to judge what the capacity of WC is and that there is a limit. If they limit this more you'll see it reflected in the ticket price, and I'm sure you'll be back on here to complain about that. Theme parks are a business. Surprise!
Did you know that lightning can commonly strike 10 miles away from a storm, and has been known to strike up to 20 miles away from an associated storm? Probably not, but Busch Garden's does. Hence keeping your safety in mind.
If Mach Tower was that important to you, you should have called ahead. As with any new ride it can have glitches. I always call ahead to confirm that any ride that is THAT important to me is open. A closed ride is not going to ruin my day.
"Malfunctions" = ride safety system. Rides have sensors and computers. They keep you safe. Do you ever have computer trouble? Car trouble? It's the same thing. No technology is immune to the occasional glitch.
It sounds to me as if Busch Gardens offered you more than enough compensation for your visit (After all, I'm sure you stayed all day in the parks anyhow and now expect a refund). Did you go to First Aid at the park? You should always report any injury to them so that they can look at it and do any necessary safety inspections. If you plan to leave right after that, I'm sure they would have given you a complimentary ticket to come back and walked you out of the gate.
Please feel free to post any more pointless, misguided rants about theme parks that you might have. I'll be here all day.