Hawk

I am negotiating a Firm Fixed Price call order under a single award BPA. The PWS is for services on-site and off-site and states the number of FTE required . My price proposal uses 2080 hrs per FTE, but the contracting officer has stated 2080 hrs is not allowable if our awarded contract rates account for vacation/holidays and that we should revise the proposed hours to 1920. Since this is FFP, aren't the hours reflecting the effort to complete the work and not necessarily assigned to a particular FTE therefore 2080 hrs is allowable? Or, because they specified the number of FTE - am I limited to a T&M-like 1920 hours (disguised as a FFP)?