i've faced this situation so many times and it's really tough. the best way to deal with it is look around at the market and see if there are better options. if all other similar buildings are priced at your new rate you both have no choice and no real way to argue it. if there are options you should both negotiate and prepare to take those options.

i have no love for large landlords in general but property taxes went up an incredible amount over the past year, easily >$500/mo on a 2br