You can’t. Your choices now are to either pay what they are trying to extort from you or wait and see if they try to take you to court over the alleged debt.
They may never take it that far and even if they did, they may simply discontinue before any hearing when they realise that you are not backing down. Then again, you could defend against any claim and be successful and not pay a penny to them. If it does go to a claim, you will have an opportunity for compulsory mediation with them and see whether they would accept an offer that is less than the claim amount.
If you want advice on the best course of action to take, please provide some background as to why you have changed your mind after ignoring all the previous notices. Please show us the original NtK and tell us the location.
You can safely ignore DRP as they are just a debt collector and have no powers to do anything. Never, ever, ever, communicate with a debt collector. They are a third party unconnected to any alleged contractual breach by the driver.
So, do you need assistance and advice or not?