You could point out to the PM comparable properties around the 350 mark or less.Hopefully, she will take into consideration what else is available around here for either 350 or 400.
I gave my tenant in Melbourne a notice of intention to increase the rent and she emailed back a list of properties for less rent. Of course they were all crummy, so I (nicely) let her know if she wanted to move to one of those crummy properties for $5 a week less, it was up to her. She did!
Of course if the PM is any good, they will know the comps in the area.