Hi there... thought I'd put my two cents in, for what it's worth.
I taught at a FADS, and now have my own independent studio. I opened my own studio just as much because ballroom courses through my veins just as much as blood, as for the reason that I think franchised studios have it backwards. FADS is very particular and very rule oriented. They are VERY against independent studios, which they refer to as "pirates". You are not wrong for going and checking out other studios if you feel it's time to make a change and your interests fall outside what they can offer. I think the only downfall here was maybe sharing with FADS that you were exploring other options, until you were ready to switch.
Here's their thinking: Learning from multiple instructors causes confusion. Instructors have MANY different teaching styles, and may give you conflicting information to get you to the same end goal. What they are afraid this translates to you is that one is right and one is wrong, or worse, one is better. Ego has a big role in it.
I'm sorry for the frustration. Keep to yourself, but explore teachers until you find a right fit for what you want, then stay put until your needs/wants change. For what it's worth...
Hugs,
T