The representations you made were out of time, so the council was within its rights to disregard (i.e. ignore) them. You must therefore tick box 1, indicating that you did not receive the original PCN (which is true), the fact that you did not receive the PCN is what prevented you from making representations within the orignal time limit.
Note that you can't just sign the form, you need to either go to your local county court or local magistrates' court to get it sworn, this is free but you will have to call up to make an appointment first.
Alternatively, any high street solicitor can witness you signing the form for about £5 - £10.
Once the form has been signed by both yourself and the witness, you can email it to tec@justice.gov.uk with the PCN number in the subject line. Once that's all done let us know and we'll advise on the next steps, but I can tell you now that I don't anticipate you having to pay a penny.