United Breaks Guitars
This is one of the most famous service failures in history. With the reputation damage this video created (> 11 Mio hits), they could have given him a golden guitar.

United Airlines
This is what Brandon Schauer calls the Service Anticipation Gap (SAG). Imagine what a customer expects after watching this, and now an employee has to fulfill that expectation. Impossible (Dragons? Swords?).

Jet Blue
Then in contrast compare this. The commercial is engaging, funny, and the employee has a chance of actually fulfilling the claims made in the ad.

Tesco
Experiment for a new shopping experience. Adapting to user behaviour.