Free Traffic Legal Advice

I can't see a loading exemption flying when you say you were parked there all day.

As regards just escaping home to Bonnie Scotland and escaping enforcement, I'm not sure what the law permits. I had a look on the internet, and it is quite clear that an English CCJ can be enforced, but in the PCN enforcement process, there is no possiblilty of a CCJ, because debts are registered at the Traffic Enforcement Centre (a special form of county court, which has no courtrooms or judges), not a County Court. I suppose you could try it and see what happens !

Well done !!

Should I send the TE9 form to TEC before I get my hands on the OfR?
As far as I remember, there was a 10 day or 21 day rule.

You must first check with TEC whether the PCN debt has been registered. Once it has you can submit your TE9. If the PCN is not registered they will just reject your TE9.

If you have screenshots of a glitch that may help. What time was the extension 'started' - you usually can't extend a session after it's expired.

+1
Most extension facilities that I have experienced require the session to be extended to still be running.

There is no legal mandate for the discount to be offered when a council rejects informal reps, but most councils do so, Havering being the exception.
However, if Harrow have not re-offered the discount it is now a complete no-brainer to register an appeal at London Tribunals and get an unbiased judgment. It is a no-brainer, because the penalty remains the same and there are no additional costs at all. If you lose, you pay the £110, and if you win you pay nothing.

We really need to see a photo of the board that shows the conditions of use of the car park.

My thanks to SFM for doing the research ! It may well be useful therefore to submit representations on the lines you suggest in your narrative, emphasising that no traffic was held up. If you like, post your proposed reps on here for review before submitting.

Google Street View is of little value here, because it is way out of date, the last view being 2019. The video and photos on the Harrow website show the double-red lines where you stopped adjacent to your car, so the PCN is legally valid.  I have to say it's a bit of a money-grubbing PCN because as you say, you did not interrupt traffic at all. You need to realise that PCN penalty income is now a huge money-spinner for London councils and Transport for London with revenues from penalties now well beyond £650million per annum.

By all means submit representations on the lines you suggest, but don't expect a favourable result. You state in your narrative that you stopped to pick up your elderly mother, but the Harrow video shows her alighting from the car not boarding.

As the discount period is 21 days, I suggest that before submitting your representations, you wait a bit to see what the others say here. However, don't miss the discount deadline if nobody else suggests any alternatives if you are not willing to risk the full PCN penalty.