Who replaces mailbox door: owner or association?

Who is responsible for replacing a mail box door? The mail boxes for all the units are in a central location. Actually, they are on the outside wall of the building which houses the clubhouse & the association office. The postal person enters the building & fills the mailboxes from inside. The mailboxes are in banks or sets of 10. I noticed the whole set below mine was recently replaced. For the past few years they insist the mailbox is my responsibility & refuse to replace or fix it. Meanwhile, I insist its a common area which makes them liable for all the mailboxes. Please help ASAP. my mail ends up all over the ground. Thanks, Joe in Miami.