You parked in a marked bay; OK, there were no carriageway markings but there is a sign. So why didn't you go and look at the sign ? It is encumbent on you when parking in such places (marked bays) to check for any possible restrictions there may be for the bay. This applies even if you are a BB holder.
Having said the above, the bay may not be marked correctly, but I'm not an expert on this, so see what the others say. Please also post the back of the PCN as it may contain errors that make it void.
Edit
Having looked at GSV, (Nov 22), the bay used to be shorter but was lengthened after April 2021, (previous GSV view), but the double-yellow lines were not removed.
https://maps.app.goo.gl/AC9UqN5cyDSJts4J8and Nov 22
https://maps.app.goo.gl/VpVYxYipg9BqXrt78We often see things like this, and one has to wonder at council Highways Department competence. However, whether this incompetent change to the street markings would win an adjudication is another matter, but it could because a bay cannot have double-yellow lines because this means No Waiting 24x7, so how can there be a bay there at all ?
Anyway, see what the others say.