Postal Locations

We have lived in Hagerman 12 years and had a post office box at Hagerman post office .In Jan we received a box rent notice, being seniors we are payed once monthly our moneys come in on the last wed. of the month. I was able to sen.d payment on 24th to late I was told yesterday. I owed 2 dollars more ( late fees) They had sent rent statement back with my check inside. I did’nt look inside thinking it was a receive. Meanwhile all mail was sent back to senders hence late fee payment added on for non payment. Today I have a mailbox at house. Was I notified (once) notification card (maybe?) l thought after additional 2 dollars was paid everything be fine or cleared up no, bills were sent back to sender (late fees) added for non payment. My question to you is why such a short payment time, senting mail back to senders not notify customers of a problem and working with seniors we pay taxes too Note( this isn’t the first time eather.