It is not a bus lane PCN, it is a Charge Certificate, served because no response was received to the original postal PCN, (paymnt or representations). A CC adds 50% onto the original PCN penalty, and means you cannot submit reps, only pay it.
However, there is a very simple way to revert back to the PCN stage. You wait for something called an Order for Recovery, (which has £10 added to the CC amount). You can then submit a Witness Statement to the Traffic Enforcement Centre that you did not receive the PCN. The matter is then set back to the PCN stage. The council will then serve a copy of the PCN, which you can then pay or appeal.
Don't let them browbeat you with threats of "County Court" because only TEC are involved, a form of court without court rooms or judges. There is no possibility of a CCJ whatsoever.