I've been having the same issues. I got no mail for 5 days one time, not even junk mail - and that NEVER happens here. I also had a check that I mailed out for a bill returned THREE times, despite my having contacted the company to verify their mailing address. I eventually called the post office on base and asked just what the feck was going on. Here's the scoop:
The USPS has gone to a completely automated system, which makes for all sorts of issues. They've also started shipping mail to out of town sorting offices when the local mail sorting place gets backed up. For instance, the mail the my doc sends me from St Louis sometimes takes 10 days to get here. Ten days, for a total of 18 miles. It boggles the mind. Anyway, it sometimes takes that long because the local sorting place has gotten backed up, so mail has been driven to Kansas City to get sorted. They send it FURTHER away from me so that it can come back to me. And, in the time it takes for that mail to get sorted at KC, the St L facility has gotten rid of it's backlog so it would have been just as quick to leave it where it was. I joked that that's one reason the price of a stamp has gone up recently, so the USPS can cover it's gas costs for driving my mail all across the land. The man on the other end of the phone said that it wasn't no joke, that that's one of the reasons for the increase.
I don't trust the USPS anymore. I've experienced and have heard of so many cases of mail going missing or not getting to it's intended destination in one piece or a reasonable amount of time that I've lost all faith in it. I only have one bill that I pay via the USPS anymore, and I'm going to see if I can't change that - and if I can't, I'm sending that sucker registered mail. I don't care too much about the cost; the peace of mind will be worth it.