Recently I was denied a receipt, when I had to pay a fine to an LC company for not complying with all their rules.
I can understand the strict rules in order to keep competitive prices. In other hand they fail a lot on their obligations. I needed a receipt as a proof of payment and that was denied. After insisting I was told I could get one e-mailing the company (intersting situation... how could I prove the payment?) Other, more extreme situations happen, like lack of support to passengers when there are large delays on flights.
It's becoming more and more frequent. Rules are becoming a lot more strict with air plane companies (not only with LC). The customer is the weakest link and is in a very vulnerable position on an airport, specially if already standing next to the gate. What can one do in such a situation?