Careless and lazy postal delivery

Looking for some advice.  Live in a rural 25 unit condo, central mail
box for all.  Over the last two years the mail deliverer has
misdelivered Jury summons bank cards credit cards, medications etc
etc.  At first I started to deal with the local postmaster directly
unfortuantely this was not a productive venture.  I went to the
consumer division of the PO and they supposedly tried to initiate some
corrective measures which consisted of marking the back of the
mailboxes with names and numbers, monitering actual deliveries etc. 
After each of these corrective measures ended the post person reverts
to her "I'm in the union" you can't prove it and your lucky to get
your mail mode, and continues to carelessly deliver the mail.  She has
I understand given different reasons for her "problems".  Similar
sounding names, box with name and number not clear enough, different
street names (my favorite), bottom line is she is lazy and careless
(words of people from within the PO not mine)  and apparently
protected from serious work rehab by the union steward.   The new
postmaster (this must speak volumes) is now going to try to deal with
it.  Other people in my condominium have also complained but as they
are intimated by the unspoken possiblity of not getting mail or having
it misdelivered,I remain the vocal component.   Unfortunately this has
produced a situation where nobody apparently can impact the delivery
persons attitude about the "jobs program" she has found.   Anybody
have any suggestions about where to go or whom to contact about a
remedy for this disaster?    RN