On a trip to Europe last winter, United Airlines lost my luggage during a connection at ORD. I landed in Germany in the dead middle of winter without any clothing, and not a single United employee in person or on the phone could tell me what had happened. Two days later, after dozens of calls and an accumulated 8 hours on the phone (90% of that time was spent on hold), my luggage was finally found. But the issues didn't end there. The flight number of the flight I was told the bag would come in on was incorrect, twice, and their incident tracking website (BagTrack) did not update once during the entire fiasco. My luggage was delivered 4 days late, unannounced, by a random third party courier. Mind you, this happened merely 12 hours before we had to leave the city we were staying in.
I spent over a thousand dollars in the first couple days attempting to repurchase the contents of my bag, assuming it was lost for good. The only silver lining to this nightmare of an experience was the fact that United refunded me the cost of replacing my clothes... a whopping 6 months after filing a claim. Needless to say, I'm ecstatically cheering on their demise.