Thank you for your response sorry I am trying my best, I am just very nervous and worried and probably not thinking straight
As I have said earlier, the railway think you have fare dodged on other occasions.
If they're wrong, then say so ('You have said that I didn't pay the right fare on previous occasions. This isn't true '.)
But if they're right, then you need to agree. If you tell them how often then that will show the railway that you are trying to co-operate.
If you have been buying 'short' tickets that don't cover your whole journey, then you need to work out how often you have done this and say so ('I estimate that I did not buy the right ticket on x occasions in the last y years'). These days, most tickets are bought with a debit or credit card, so there's a good chance that your bank/ credit card statements will tell you when you bought tickets which were less than the full fare: if that doesn't work for you, then think about when you would have fare dodged: if it was every time you went into the office, you will probably know when that was; if it was (for example) the end of each week or just before payday when money was tight, you can work that out too.
One way or another, you can get fairly close to how often you fare dodged - and as long as that's pretty close to what the railway thinks, that should be good enough (if they think you fare dodged 20 times and you think it was 19 times they will probably be ok: if they think it was 20 and you think it was once they may have a problem). But you need to show that you are trying to be honest!