Free Traffic Legal Advice

Advice please.
PCN from driving in LTN zone Langton Way/Dover Road SE3. 
06/10 contravention, date of notice 23/10

I am at fault and did not see the poor signage at the junction.

My biggest issue is that I know I have done the same journey at least another 3 times between then and now, so I will have huge bills racking up.  Any advice on how to contest this at all?

On researching this junction, others have said "This entry to the LTN is particularly poorly positioned in my view. There is no advance warning and the sign and camera are immediately on the junction turning into Langton Way. As the junction is a roundabout, doing a U turn is almost impossible even if a driver sees the sign."

DROPBOX photos here:

Does anyone have any advice on appealing against having to pay this fine multiple times?

Many thanks in advance.

I am at fault and did not see the poor signage at the junction

You're not at fault at all if the signage is poor !!  Poor signage = inadequate signage and 'adequacy' is a key requirement within Regulation 18 of The Local Authorities’ Traffic Orders (Procedure) (England and Wales) Regulations 1996 
https://www.legislation.gov.uk/uksi/1996/2489/regulation/18

However, if you are to win on inadequate signage, you must describe why the signage is inadquate in order to get the council to try to prove its adequacy. They will probably supply a load of guff. Do be aware that whatever representations you submit to the council, they will reject them, no matter how valid they are. They do this because they know that most people (>95%) then cough-up, the council having cunningly re-offering the discount.