Who else has been having issue's with us postal ground advantage ship time's?

We ship thousands of packages every month and rarely have more than a handful of issue's with us postal within each month. Starting last month though, us postal has slowed ship speeds down to weeks from days. We have had to file dozen's of claims with lost packages. Had ALOT of AZ claims filed because amazon's system tell's the customer the part will arrive on specified date, but is never correct since usps slowed down ship times, so customer's then file a claim and are refunded, even though packages do arrive eventually. Amazon's ship time setting do not allow for these kind usps ship time settings and no UPS,FEDEX,USPS priority mail are not option's for these kind of products and we ship all order's within hours of receiving them, seven days a week.