Hoist/Cohen’s/Tomlinson help

[Grabo]

Hi I had a Barclays Partner Finance loan that was transferred to Hoist/Robinson Way and they took me to court in June 18, I was on hol at the time and only had limited time to act. Ended up with a Tomlin order and agreed to pay £100 per month. Long story but Robinson Way never set up a ddm and I stopped paying in March 2019 due to a mix up with another regular payment to Lowell. I realised the mistake last year (Barclays had sent a couple of letters saying that the debt was being reduced by over £150 due to their errors in the past). Then in July 2020 Hoist marked the account as closed on my credit file so I thought that was the end of it. However I have now received a letter from Cohen’s asking for the full balance (£5900) or they will issue a ccj. What is my best course of action, would it be possible to start paying £100 per month again (and is it not strange that the account was closed Anne no debt showing on my credit file?) please help thanks