You need to get the statutory declaration (form PE3) sworn at your local county court or magistrates' court (free of charge), or you can do this at any solicitor for a small (£10 / £15) charge.
Then scan it and email it to tec@justice.gov.uk with the PCN number in the subject line, don't send it in the post as that just adds a risk of postal problems which you don't have with email.
Once that's done keep an eye on the amount due on
https://parkingpayments.lbbd.gov.uk/3sc/ and as soon as it's back down to £65, let us know and we'll help with making representations. You don't actually need to receive the physical PCN in the post, you only need to know that it's been issued (which is when the penalty drops back to £65) as you can make representations on the council website.
