Your contention may be correct according to you. But I tend to agree with your FAA.
RTI can provide you only the informtion held by the public authority. According to them they have provided you the information held by them. Second appeal system is meant to deal with isimilar situation where the apppellant and the PA disagree on certain issue. One has to read between the lines of Rule A and Rule B to make any other comment. If you consider solving this issue the way you had interpreted is of paramount importance at anycost, please make your own decision about second appeal.