I am currently a tenant of an apartment complex. I've been there for almost eight months now and my lease expired. Due to the lease expiring, I am now on whats known as "month-to-month" leasing; when I signed the orginal lease the leasing office told us that when residents go to "month-to-month" rental rates are subject to change. Every month I receive a rent reminder from the property manager. This month my rent was actually cheaper by $40. When I payed my rent I also gave the leasing office the rent reminder, where I was told that it was an error and I was responsible for paying that $40 and now they are attempting to charge me pentalty fees as well. My question is, if I am on "month-to-month" and am not in a binding contract for a specified amount, am I obligated to pay for their "mistake" as well as penalty fees? Also, what do I need to do in order to avoid these charges? Thank you.