This is a new bus gate, and to be honest, it's difficult to see how you could miss it, based on what we have seen on the few other cases that have come to notice. Did you not realise what the signs meant ?
I agree it is a trap, as it's located about halfway down the street. Problem is GSV latest is March 2022. If you want to fight this, you'll need to do some legwork and take photos of any advance warning signs, (if there are any, of course !).
It may be well worth submitting representations saying you were taking your father to the hospital and were unaware if the new restriction. Main point is to make sure the two PCNs are considered together. You could request that at least the second PCN be cancelled as as well as driving to the hospital you drove your father back home, and say the two PCNs came as a considerable shock. If you can get one PCN cancelled and pay the other at the discount, you will have got the most favourable result, in my opinion.
The really stupid thing about this bus gate is it is designed to remove through traffic, yet you were visiting the hospital which the restriction is designed to benefit traffic-wise. It's all part of council barminess that we now see almost as a disease in councils nowadays.