Here is where you parked on Barrett Road. The sign allowing pay-parking is right beside the bay divider, the double-dashed line perpendicular to the kerb. I had to go back to the GSV March 2019 view to get a good view as most of the views cars are obscuring it. Were you not aware of this divider marking ? The council have not followed best-practice here. At the divider, they should have mounted two signs, side by side, each on marking with an arrow (left or right) the parking restrictions for each bay. But, as we all know, they do nothing because the PCN penalty money is so attractive.
https://maps.app.goo.gl/P9Tnk3BQvJJpPrcRAThe marking looks pretty worn in 2019. If it has disappeared you have a winning case to take to London Tribunals, but you'll have to go there and take a photo, as later GSV views are obscured and also of 2022. There is no later view.
This white SUV is on the borderline
https://maps.app.goo.gl/uxqq6WsAD4cX4PvN6If you want to take the matter further, you must wait for the Notice to Owner sent by post to the address on your V5. Is this up-to-date ? At the NtO stage, you submit your reps again, but this time informed by this forum. The key thing is the obscuration of the bay divider by parked cars, plus the signs not being mounted in accordance with best practice. The discount option is lost if you do this, although the council may re-offer it to avoid encouraging you to go to London Tribunals. If you enjoy a fight, then proceed. If you consider it to be too much of a hassle, then pay-up. Because 99% of motorists pay-up, the councils just carry on with their dodgy practices, and ruthlessly game the system to maximise the penalty payments.