Very difficult to fight these as you were either there or you weren't. I assume this is just one of the two PCNs. It might be prudent to post the other 3 pages so we can check it for errors, but it's thin gruel at the moment, I'm afraid unless our intrepid adminstrator delves into the ULEZ regs and finds a killer appeal, there is little to go on. Did the PCN arrive like that with an unreadable title ?