I have received a CCJ on my credit score

Coupon-mad

Not if you didn’t ask the Judge at the CCJ hearing to order them to pay, or at least to ‘reserve’ your costs until the main hearing re your defence to the claim.

You haven’t mentioned what happened after you defended the claim.  You should have had a second hearing about the PCN.

If you had stayed here and asked for guidance you’d have been better prepared...sounds like you got the CCJ set aside but forgot to ask for your costs? 

And you don’t seem to know what has happened about the second hearing re the claim (unless the court struck their entire claim out, which the court Order will tell you).