You can't change your defence now unless you pay £313 and even then, the claimant can challenge your right to change it.
However, you are very lucky that it is DCB Legal that have filed the claim. Although you have used the lengthy defence from MSE which judges hate and don't bother to read as they just don't have the time or patience to do so, a defence was submitted.
So, once you have submitted your N180DQ you will get a telephone appointment for a call with a mediator. This is nothing to do with the judicial process and there is no judge involved. All you do is offer £0 and it is over in minutes.
Eventually the claim will be transferred to your local county court and assigned to the small claims track. You will receive notice of the hearing date and directions on deadlines for submitting witness statement and there will also be a deadline for the claimant to pay the £27 trial fee. It is just before that date that they will discontinue.
For now, here are the instructions on how to submit your own N180 DQ:
Having received your own N180 (make sure it is not simply a copy of the claimants N180), do not use the paper form. Ignore all the other forms that came with it. you can discard those. Download your own here and fill it in on your computer. You sign it by simply typing your full name in the signature box.
https://assets.publishing.service.gov.uk/media/673341e779e9143625613543/N180_1124.pdf
Here are the answers to some of the less obvious questions:
• The name of the court is "Civil National Business Centre".
• To be completed by "Your full name" and you are the "Defendant".
• C1: "YES"
• D1: "NO". Reason: "I wish to question the Claimant about their evidence at a hearing in person and to expose omissions and any misleading or incorrect evidence or assertions.
Given the Claimant is a firm who complete cut & paste parking case paperwork for a living, having this case heard solely on papers would appear to put the Claimant at an unfair advantage, especially as they would no doubt prefer the Defendant not to have the opportunity to expose the issues in the Claimants template submissions or speak as the only true witness to events in question.."
• F1: Whichever is your nearest county court. Use this to find it: https://www.find-court-tribunal.service.gov.uk/search-option
• F3: "1".
• Sign the form by simply typing your full name for the signature.
When you have completed the form, attach it to a single email addressed to both dq.cnbc@justice.gov.uk and info@dcblegal.co.uk and CC in yourself. Make sure that the claim number is in the subject field of the email.