Luckily for you, this is just ECP and I can assure you with greater that 99.9% certainty that if you follow the advice you receive here, you will not be paying a penny to ECP.
Whilst you have now updated your V5C, that does not solve the issue that ECP now hold two possible addresses for you. This WILL end up being a county court claim and you do not want a claim going to the wrong address and not being responded to.
The first thing you MUST do immediately, is send the ECP Data Protection Officer (DPO) a Data Rectification Notice (DRN) which instructs them to update their records with your (the Keepers) current address for service and to erase all other addresses they ay hold. The highlighted words are there for a reason, so use them.
You can safely ignore any debt recovery letters from DCBL or any other powerless debt collector. They are not a party to the contract allegedly breached by the driver. All they can do is try and intimidate the low-hanging fruit on the gullible tree into paying out of ignorance and fear.
You will eventually receive a Letter of Claim (LoC) from DCB Legal (not DCBL). When you do, let us know. Eventually, you will receive an actual N1SDT Claim Form from the CNBC, which you will show us, only redacting your personal details. Leave the issue date visible and the Particulars of Claim (PoC). We will give you the advice on how to defend it with a template defence.
Eventually, the claim will either be struck out or discontinued just before they have to pay the £27 trial fee.
There are countless ECP PCNs being discussed on the forum and every one is advised the same. As long as the claim is defended, they all end up struck out or discontinued. Search the forum for them to see how they are handled and what happens when.