I was appointed as Tax Assistant(Income Tax) in Chennai on 29.11.2007, and promoted as Sr. TA on 30.12.2011. I got the promotional benefit (Viz. pay fixation by granting one increment).

I have been transferred to Kolkata on my own request on 08.05.2012. as per terms and conditions I have been reverted to TA and my pay was re-fixed ( Basic pay protected and grade pay reduced to 2400).
In kolkata, I again promoted as TA to Sr. TA on 02.09.2013 and I was granted the promotional benefit (Viz. pay fixation by granting one increment).
Whether I am eligible for the increment benefit on promotion in kolkata or not. As now audit is objecting that the fixation in 2013(in Kolkata) has resulted in double benefit since he had got the benefit of FR 22(I)(a)(1) twice in the scale of 4000-6000.
If not under which rule I should be denied the increment benefit on promotion in Kolkata. If possible kindly give the relevant part of the FR.