As stated, the driver breached the contextual terms of parking. However, if you don't want to pay penny to UKPC, then follow this advice...
All appeals, initial and POPLA will be rejected. I wouldn't even bother with a POPLA appeal. Simply appeal to APCOA with the following:
I am the keeper of the vehicle and I dispute your 'parking charge'. I deny any liability or contractual agreement and I will be making a complaint about your predatory conduct to your client landowner.
As your Notice to Keeper (NtK) does not fully comply with ALL the requirements of PoFA 2012, you are unable to hold the keeper of the vehicle liable for the charge. Partial or even substantial compliance is not sufficient. There will be no admission as to who was driving and no inference or assumptions can be drawn. UKPC has relied on contract law allegations of breach against the driver only.
The registered keeper cannot be presumed or inferred to have been the driver, nor pursued under some twisted interpretation of the law of agency. Your NtK can only hold the driver liable. UKPC have no hope at POPLA, so you are urged to save us both a complete waste of time and cancel the PCN.
AS I said, don't bother with a POPLA appeal. Ignore all debt recovery letters. Debt collectors are powerless to do anything except to try and persuade the low-hanging fruit on the gullible tree pay up out of ignorance and fear.
When you receive a Letter of Claim (LoC) from DCB Legal (not DCBL), then come back and we will tell you what to do next.
Eventually you will receive a Claim but with our advice and defence template, the claim will either be struck out or discontinued in due course.
So, you have a couple of choices... pay the charge at the mugs discount rate, try and appeal your way out of it and end up paying the full charge or go through the process of them initiating litigation and eventually having the claim struck out or discontinued. Your choice!