Quite interestingly: just doing customer satisfaction training with my present airline... (what? certainly an off topic in Wizz Air thread)
And in fact, all it says about retaining customers, applies to retaining employees:
It is 5 x 6 times cheaper to retain a customer than to gain a new one; loosing a customer costs much more than just the revenue lost: dissatisfied customers will take any opportunity to make negative propaganda for the company, either talking to friends, or publicly on the internet... ;-)
And, finally, if the company doesn't listen to the customer, the customer will find somebody who will listen outside of the company.
Wizz Air - time to learn!