I have accidentally purchased a ticket from London...

I have accidentally purchased a ticket from London Euston to Northampton which was for the 3rd of January at 14:54 and I used it on the 2nd of January because I thought it was for 2nd ( I accidentally bought it for the 3rd because it had the exact same price and hours)

Common mistake, could happen to anyone.

I arrive at the station with my e-ticket and it doesn't work when I scan it (now I know it's because it was the wrong date) so I go to one of their employees at the gates to show them the ticket, they get a good look at it and let me through.

I travel fine and when I get to Northampton I get told that my ticket is for the 3rd, not 2nd and I have to pay 29.70 pounds (which is a lot of money for me as a student) for a new ticket in order to get out of the station.

If I knew, I would've traveled on the 3rd using my ticket, it wouldn't have been an issue at all. But I was allowed to get on the train so I didn't even know I was travelling on the wrong day. I know it is my responsibility to check my ticket but it is also their employee's responsibility to check my ticket thoroughly and to inform the customer of their mistake and any expenses that come with boarding the wrong train.

I ended up paying 9 pounds plus the 29.70 pounds which ends up with me paying 38.7 pounds for one journey, for one mistake that not only me, but one of their employees made as well. Not to mention I was treated like the lowest class criminal and was asked for money without even being listened to fully. No empathy from the employees, just quick to take my money.

We all are human and make mistakes, and it's not like I traveled without a ticket, I just think it is ridiculous to charge so much for a simple mistake that not only I made, but their employee as well.

It is not fair that a person has to pay when two people made a mistake here, one of which is you, national rail.