+1
Unfortunately, cases like yours rarely end well because you are in a mess of your own making by not updating your V5C. So all the statutory enforcement documents were sent by the council to the name and address on the V5C as recorded by DVLA. Eventually, with no response to the documents, the PCN debt is registered at the Traffic Enforcement Centre and the council send out an Order for Recovery. Like the previous documents, this is sent to the V5C address. When not paid or a declaration made to the TEC the council instruct enforcement agents, (bailiffs). Bailiffs, ("enforcement agents" since 2014), are very proactive in seeking out the debtor as their livelihood depends on it. I use the word "bailiffs" because it is a lot easier and quicker to type ! Also everybody knows what you're talking about !!
Currently, you are at what is called the "compliance" stage. At this stage you can pay the debt, plus the fee of £75 and the matter is closed. The next stage is the "enforcement" stage, and includes attendance at the debtor's address and a fee of £235. After that comes seizure of goods to sell to pay the debt.
There is a legal process to seek that the matter be reverted to the Notice to Owner stage, (or PCN if the PCN was a postal PCN) and to cease bailiff action. This is to submit to TEC either a Witness Statement, or a Statutory Declaration. Which one depends on the legislation under which the original PCN was served. However, in your case, the time to submit either of these has expired, and thus needs an additional submission, which is to seek to submit the declaration "out-of-time".
As the postal PCN was served by High Wycombe council, it was probably under the Traffic Management Act, so will require a Witness Statement to be submitted, plus the form to request to submit the WS out-of-time. So you should require TE7 and TE9 forms
https://www.gov.uk/government/collections/traffic-enforcement-centre-formsOut-of-Time declarations are passed to the enforcing authority who can object to them, at which point TEC invariably reject the submission.
None of the above process is affected by any payment made to the bailiffs, hence HCA's advice to pay the sum now before you get a visit and another £235 added on.