Very poor customer service

I bought my ticket from Lisbon to Madrid online weeks before a trip that I planned with friends. I accidentally booked the ticket for the day before we were actually leaving and did not realize this until I arrived at the airport. I went to the ticket counter to see what could be done about switching my flight to the correct day. Even though there was "still room left on the plane", I had to buy an entirely new ticket for full price. Then, I went to check in after paying 178 euro for another plane ticket only to find out that my ticket was stand by! The woman at the counter never informed me that I was buying a stand by ticket. I ended up getting onto the correct flight, but only after a ton of stress and a pretty large amount of money. I realize that it was my mistake to buy the ticket for the wrong day, but any company who places even a small amount of value in their customer service would try to help me through this in the most cost effective manner possible. They would not make me unknowingly buy a stand by ticket at full price. I am very disappointed with the service at Easyjet and do not plan to do business with them again.