In the last couple of years, I have had important letters get "lost" in USPS in the Dallas area including things I sent with the USPS guarantee, signature requi

In the last couple of years, I have had important letters get "lost" in USPS in the Dallas area including things I sent with the USPS guarantee, signature required etc. and things sent to me being lost. I didn't receive any official apology from USPS; I learned from the local news there was organized crime ring regularly opening up letters they thought contained checks. To make it short, USPS has forced me to stop send checks or anything important through the mail.