Buying prescribed account and think they can get away with collecting on it

Im so upset with this people, they bought a prescribed account of mine at Markhams, my last payment on this account was almost 7 years ago and they have bought it last year and ever since last year its reflecting again on my credit bureau report. I called them and when i asked them when they got the account by Markhams they said last year but have never even tried to make contact with me as I have been living at the same address and works for the same company for the past 20 years. I have emailed them plenty of times and requested for a clearance letter as by law they are not suppose to be having this account listed anymore. They kept on responding with bot responses saying they liasing with there client and will than respond, up untill today no response was received and now they not responding to my emails anymore. This will be taken to the client protection at the ombudsman as u are just wiping your buds with my emails and i will not stop untill you remove my name from the credit bureau