THE CABIN CREW STOLE ME CASH!!!!

Lest month I travelled to Bordeaux with EASY JET and on my flight back, apart from my flight being delayed almost 3 hours and I had to miss 1/2 day of work, my biggest dissapointment was the fact that Easyjet STOLE me GBP5.00!
I ordered a sandwich ()so hungry after such a long delay!) and the staff didn't have enough chage, so I was told they would give me GBP5.00 back later on. No one came back to me, so after a while I reminded them about my 5 GBP, which they still didn't have. We ended up landing, and before leaving the plane, I asked them again for my money and their reply was (this was from the Senior Cabin Crew one!): Sorry now it's too late. We have closed the bag where the money is and we are unable to give you any cash back. Now You will learn for your next Easy jet flight that you have to make sure any moeny is given back to you before the landing! ---- I was really shocked with the lack of customer service, the rudeness and specially that they kept GBP5.00 of mine!!! I know it's just GBP5.00, but it's question of principles!
I complaint throught customer service department, and they didn't do much, just apologies for the cabin crew's behaviour and they assure that wouldn't happen again (how can they be that sure that won't happen again? And what about my money????)
After insisting they agreed to offer me a discount of GBP10 when booking my next flight ON THE PHONE.
I needed to buy another flight for January, checked the times and prices online and called them to book my flight. GUESS WHAT??? When booking on the phone, flights are about GBP30.00 more expensive!!!! So what is the deal???? You pay GBP30.00 more (plus the cost of the expensive especial phone number!) and we give you a discount of GBP10.00, so we steal you now GBP20.00???
I contacted them again to try to find a solution, but they don't care AT ALL. They prefer to lose a loyal customer (I book around 12 flights per year with easy jet) that to refund me some money to my credit card or to offer me a REAL DISCOUNT.
So yes... after this big dissapointment I have swear I will not put a foot again on an easyjet plane, and so will do my family and friends.
This will not finish here. I do work in Tourism, in a Tour Operator, and I will not offer again an easy jet flight to my clients.