The same thing happened with me with the TO exam. I previously worked for MTA also. I wasn't stressing the letter at the time because I had other matters to tend to. Now my focus is on asking around and making some noise! IMO this tactic is more retaliatory than anything else. MTA expects you not to question or fight it. Don't let that stop you. Fight it!! From my understanding , that 3 N 1 rule is for promotional exams only. I'll keep you posted on my situation.