Post Office review: missing mail 1

We were out of the country for 2 weeks and had requested the mail to be on hold at the Post Office. When we returned, the box door was not shut and there were a few unimportant junk mails inside the box. Next day we went to the Post Office to pick up the mail, and there were unusually just a few pieces of mails collected. During our 2-week absense, many bank and credit card statements should have arrived. So we contacted the manager - Mr. Richardson at the Post Office. At first he was saying we should check with the carrier. So we waited the next day till the lady carrier appeared to deliver mail at our apartment. She claimed that our mailbox door was open. Then we argued that no mail should be put into an opened mailbox, let alone we had our mail on hold! So we called back to Mr. Richardson, he became very unfriendly and said he and his office were not responsible for mail loss, even told us to complain to US government. And he hung up on us. What kind of attitude is that! He does not deserve to work for the government. And for us, worse yet, due to the mail loss, an updated credit card mailed to us during that time was lost and misused badly for over $3500. That is really upsetting, and we are still trying to find out how to resolve this mess.