Don't rely on ChatGPT for a start !
All you can really do is submit representations stating that you checked whether you had to pay for a motorbike with ChatGPT and it told you no payment was necessary, and ask that on this ocasion only, they cancel the PCN.
HOwever, ChatGPT has to get the information from somewhere, so one must assume that "somewhere" is Transport for London, so check their website..
PS: I did a quick check with a Google question, and their AI says yes you must pay, but its a lower charge.
