I've had UPS lose packages I've sent, or deliver things late since the first time I used them, in 2000. My most recent experience was with an Amazon order, they claimed to have attempted to deliver when they didn't (we were at home all day).
They then promised to do it the next day, but didn't. About one out of every four or five orders I have delivered via UPS from Amazon have a similar problem.
I'm not sure why they keep using them, I understand it may be cheaper, but if you keep having orders canceled or having to give months of free Prime membership due to their incompetence, is it really worth it? Not to mention that this makes me want to shop elsewhere.
Reason of review: Poor customer service.