PA Unreasonable Move-Out Charge

I recently moved out of an apartment and was charged $300 for door damage charges and lock out charges. However, I wasn't responsible for the broken lock at all - it was simply out of battery. I went straight to get help from the maintenance guy without filing a request, who spent the entire afternoon trying to fix it and eventually had to break the entire lock and replace it with a new lock.

I called them and was told the maintenance guy has left and all those front desk people have also left. They also said they no longer accept dispute and because there wasn't a maintenance request, they cannot do anything with it. They said they demand immediate payment otherwise there will be collection efforts.

What should I do at this point?