If you want to challenge these discrepancies the only way to do so is to plead not guilty. You will then face a trial where you can have the people who provided this written evidence attend court to give their evidence in person.
Then you will have the opportunity to cross -examine them in an effort to persuade the court that their evidence is unreliable. And they will have the opportunity to clarify or correct any of the mistakes or discrepancies you believe they have made.
The cost, if you are unsuccessful, is the difference between about £90 in prosecution costs they will request if you plead guilty and about £650 for a trial. You will also lose the one third discount you will be given off your fine and surcharge which you would be granted for a guilty plea.
If you take home £500pw that difference will be about £900.