Can a home loan company not accept your monthly payment when you get behind?

I fell 1 month behind I called to take to a loan manager and she told me they will not accept my payment until I pay the full payment They told me any payment I send they will send it back to me. I am hoping to be caught up by the 15th but they are not willing to work with me and now they are telling me I can loose my house if I don't pay up by the next due date. I am upset I am only one month behind can they do this to me? Can they reject my checks I am willing to work with them, The lady told me she didn't know what to say and there was nothing they could do for me. What do I do