As a business owner I can say that the customer service side of OnTrac is the absolute worst. If I ever need to call them the hold time is ALWAYS 45 minutes, they'll lie and say it's an "unexpected" high call volume, it's been this way for years.
The shipping side of OnTrac seems to be good, but when you need to contact them it's a pain. You can't even call them to schedule a delivery unless you want to wait on hold for almost an hour.
When I want to pay OnTrac MONEY I can't even do that, they don't have online billing, I have to call and wait forever just to pay them. UPS isn't much better. I wish DHL was still around.