Its normal for a part 61 FBO flight school to slow down this time of year. The money is being spent on the holidays. Most everyone's budget gets tight and taking flight lessons is not the priority. The other thing is the weather- depending where you are- people ussually don't want to fly in the cold and ice.
I don't think the flight school blacklisted you. Its just hard to commit you to their customers when your availability changes. And "out of sight out of mind." The fbo schools don't have the revolving door the 141 pilot factories have.
I find it odd that they had you sign a 2 year training contract for that type of gig. Did they send you to SIMCOM or formal training? If so, thats not really expensive enough to warrant a 2 year contract. How much do you own them if you leave?