Apologies for not getting back earlier. However, you’ve received some good advice already.
The debt collector stage that you’re at right now is not concerning. In fact it is good.
As pointed out, there is a 6 year statute of limitation for civil claims in England. That statute runs from the date of the alleged contravention, not from the date the PCN was issued.
Even if any PCN was actioned on today, they would have to issue a Letter of Claim (LoC) which must give you 30 days to pay or respond. If you respond on day 29 with a request for another 30 days to allow you to seek debt advice, they are obliged to delay initiating any claim by that period.
So, even if they issued an LoC tomorrow, 23rd January and you follow the advice, they would only be able to claim for PCNs issued after 23rd March 2019. So, for now, you only need to be concerned about PCNs for alleged contraventions after that date and for every extra day you don’t receive an LoC, you can extend the date they cannot issue a claim for the PCNs.
Right now we do not know whether the PCNs that you may be liable for are PoFA compliant, especially from 6 years ago when a lot of these parking companies were not as switched on.
Apart from the DRN, I would not do anything else unless an LoC is received. Once that stage is reached, we will have a better idea of how many PCNs you are potentially dealing with. When responding to the LoC on day 29, you can request evidence of the NtKs and that will then give us a better idea of where you stand as far as defending any potential claim.
One thing is sure, if they use DCB Legal as their bulk litigator, there will be serious flaws in any Particulars of Claim (PoC) which can be exploited.
It would be useful if you could list all the PCNs that pertain to contraventions (not the issue date of the NtK) after 23rd March 2019 to get a better idea of how big a claim they are able to make should they actually progress it that far.