I respectfully disagree with the notion of requesting a SAR, at this stage. Additionally, there is no requirement for the OP to respond to anything, including an LoC.
I'm not saying they shouldn't but in my experience, it has never made one iota of difference to the outcome of a UKPC/DCB Legal claim as long as the claim is defended using the template defence. The very few that ever got as far as a hearing, and that was due to ****-ups made by the defendant by not following the advice properly, prior communication with UKPC did not enter into it.
The OP can send a SAR and receive all the necessary information but when the claim is served, and it will be, they cannot ague in their defence that they cannot fully understand what is happening based on the woefully inadequate PoC that DCB Legal will serve.
The current recommendation over on MSE is that a SAR should not be requested until after a claim has been served. The PoC will say that the defendant is being pursued as either the driver or the keeper.
Let them serve the claim. The PoC will be inadequate which, in itself is an abuse of process. You can guarantee that the sums claimed will be mendacious. They will claim that £70 are for "damages". They will be in breach of PoFA 4(5) by claiming for more than the amount on the original PCN. They miscalculate the interest and will not have provided any reference dates to prove their calculations. They will say that the PCN was "issued" on a date. However, the date they use is the date of the alleged contravention, not the date the NtK was issued. We don't know the date the PCN was issued if they don't correctly state it in the PoC. Interest can only be calculated on the principal sum from the overdue date to a fixed date on or before the issue date of the claim. None of those dates are known. All breaches of due process and grounds to request that the claim be struck out.
Let the bottom-dwellers make their mendacious claim and provide added ammunition for them to realise that if they let it get in front of a judge, they are likely to get a spanking. They will discontinue before they have to pay the hearing fee.