Hmm, lots of advice here, but the unfortunate fact is that, at the very highest level in the MoD, such occurrences are condoned. The complainant is more likely to be disciplined. In this case, as it would be a civvy complaining about a serving officer, the civvy cannot complain to her own Personnel/HR/Welfare etc, but must do so to a more senior officer in the “offender’s” Service. This senior officer need not know either party and is permitted to make a ruling without taking or considering evidence. (Same applies in civvy vs. civvy).
My advice to this unfortunate lady would be that, if she wants to continue her career in the MoD, she politely seeks another posting. This is the formal advice most often given in these cases. Alternatively, get a good digital recorder and gather evidence that way. I wish her luck.
For the record, I don’t agree with most of the above, but it is underpinned by formal rulings, obtained under FOI.