NM landlord tenant law, is a landlord allowed to charge an additional fee that was not covered in the original lease

Lease agreement: My daughter is renting an apartment in Albuquerque NM. She just left the country on vacation. She got a note from the apartment complex that her lease agreement had to be signed before the first of the year or a 50 dollar fee would be assessed. She called the office and talked to the gal working the weekend shift and explained the problem. The gal told her to not worry---she could sign it when she got back. Before she left (5 minutes before we took her to the airport) she wrote her Jan. rent check and a hand written note stating she was going to extend he lease for the next six months and signed the note. When we stopped by the office and dropped off her Jan. check and signed note the "Top Manager" said there were no exceptions and she would be charged the 50.00 fee. We asked if we could sign the lease agreement for her and were told that she had to sign the agreement (she is 23 years old) and would be charged the 50.00 fee. Is she legally accountable to pay the fee? - Is this your question? Add additional information