If its a private firm, ditch every warning letter, do not respond to any letters threatening court summons, they will give up trying to trace your address.
I had the same, photo of my car landed on the mat for parking and leaving parking area and leaving site to visit Toys R us next door. Bill went from £60 up to maximum £300 , then as time went on, ( months) different bailiff letters from different company's as each one had passed the case on as I'd not responded, the bill started getting cheaper to tempt me to respond lol.
They gave up after about 8 letters and now that was 2 years ago...