As per instructions, please post one of the PCNs, all sides, plus anything else that is requested there: -
https://www.ftla.uk/civil-penalty-charge-notices-(councils-tfl-and-so-on)/read-this-first-before-posting-your-case!-this-section-is-for-council-tfl-dartme/GSV is not sufficiently up-to-date, being May 2023, but a clear yellow line is shown. This means that as a motorist, you are under a duty to look for the sign governing that yellow line. You say it was there but low down or at least not on a pole, but it was there.
https://maps.app.goo.gl/RwtMiMS7QvoDe4aY8If you can provide photos of the sign it would help us. Certainly you have a good point about sign obscuration, but you need to prove it if you want to win this, and the only credible place will be at the Traffic Penalty Tribunal, the council will just fob you off, as they already have your money. It is a total no brainer now to submit representations to the council and once you get their Fob-Off letter, register an appeal at the TPT. This is because you have already paid all there is to pay and you could get it all back at no additional cost to yourself if you win.
