We took lessons from a chain too. We spent thousands and knew little more than how to do a box step - although it was a technically correct box step.
We felt like the pace was incredibly slow and that the intent was to suck more money out of us. Listening to the pitch about buying the next block of lessons was about like talking to a used car salesman. It was hard to get a straight answer on how much it was really going to cost, or what we would be getting for our money.
Strangely enough, when we first signed up, we asked us what our goals were and we said we wanted to be proficient social dancers. The rony is that only knowing how to do a box step actually handicaps you on the social dance floor.
Finally, we wised up and began taking classes with the local dance group. Classes usually run $7 per person per lesson -usually a 1-2 hour lesson. You can actually take private lessons with some of the instructors (I'm not sure if they are certified).
While we appreciated all the nuances of the box step we were taught by the chain, we have learned more in six months of taking lessons locally than we learned in 18 months with the chain - and we have saved a lot more money.
I guess in the end, it depends on what you want out of your dancing experience.