Hi all - Hoping for some help please

Yesterday I had a letter from Mortimer Clarke. I have had these previously but from previous advice I had ignored them.

The letter is regarding an old CCJ originally from Black Horse dating back to probably 2010/2011....not sure on the date but it came off my credit file 2018/19.

I was repaying this debt via AOE 20 pm until my employer shut down in April 2018 and the AOE stopped. I didn't have any details of it by then to be able to transfer it to another employer etc. (not that I particularly wanted to).

Since 2018 I have had the odd random letter through regarding this and an odd call from Cabot who left messages on my voice mail. We moved in November 2020 and since we have lived in this house the letters have become more regular.
This year I've had a few which I have ignored. These letters have no details of the original CCJ on them, they are re: ME 111 ltd and myself for approx 7k. They refer to these details and the "CCJ obtained against you in this case". No further information.

The latest letter says that as they have not been able to speak with me "our client has requested that we instruct Marston to visit you at home. The Marston rep will put you in touch with us so that we can work with you to come to an affordable and sustainable repayment arrangement"
I have 7 days to respond from date of letter, which means I would have had to be a mind reader as the letter arrived after the 7 days had passed!

I have been told by another person that Marstons would probably be acting as a high court bailiff in this case rather than a debt collector as a "debt collector" wouldn't get very far but that letter doesn't scream we're sending in the baliffs to me?

I could ask them for proof that they have made the relevant court application to transfer their interest at court on the judgement from Black Horse to ME 111 and for clarification of the original judgement and amount etc but I have been warned that by doing this it could prompt ME111 to do this and then that may risk an entry onto my credit file - I don't want that!

So I am stuck what to do - do I carry on and ignore (and get home visits form Marston) or do I poke the bear and ask them for clarification of the debt or do I just speak to them and arrange a payment plan.

I have also been told that I could go straight to vary the judgement at court N245 form to prevent enforcement and to protect my credit file. However this would mean giving court details of my new finance agreements and them also being wrapped up into a payment plan and probably ultimately having something on my credit file from my new arrangements!

I feel that they have no details of the CCJ otherwise surely they would have the details on the letter?

Any thoughts/help gratefully received