On arrival to catch our flight to Cefalonia yesterday we discovered our ticket was for year 2017 not 2016. We had already stayed the night at Gatwick, paid for rooms in Cefalonia and got a hire car. I returned to the hotel and immediately tried desperately to change the ticket as I had only just booked it a few days before and it was obviously a computer error. To my dismay a company called on the beach were rude, unhelpful and tried to charge the full price again plus an extra £200. I then called Thomas Cook who told me to call On the Beach and so it went on. My partner and I spent the day waiting to get the car out of the car park and finally drove home. This morning I immediately called Thomas Cook a guy called Fabien told me they could change it and had availability from the 13th September to the 24th for a price change on the tickets of £144. They advised me to get the last four digits of the card number On the beach used to book the ticket. I did this and then called Thomas Cook back to change the tickets, by this time I got someone different who refused to change the tickets and told me only On The Beach could only change them themselves. I then spent another hour unable to even get through to anyone at on the beach at all.In the mean time the hotel (Fotini Apartments) id booked in Cefalonia only two days previously refused to cancel the booking or even take just one night and charged us for the full three nights. Along with that we had to pay for the hotel and parking in Gatwick. Despite the fact of it being an obvious mistake no-one at On The Beach were prepared to help in anyway, even though Thomas Cook were more than happy to change our flights for a nominal fee. I book flights constantly as I work abroad and have never had this problem before nor had to deal with an agent like this. This is obviously a mistake and as we live next to Stansted not Gatwick the last thing we want is flights for next year from Gatwick. In the end we have now had no holiday, yet paid for the hire car, hotel despite begging them not to and they have rerented the room and our flights. We do not have any travel insurance at the moment either. I would be so grateful of any help on this matter this has been extremely stressful for both my partner and I and to top it on our return from Gatwick we got caught in a massive traffic jam !!! I feel that it was the mistake of the travel agents site re the date mistake and not my own.