Computech Credit Services at it again

I have never heard of this company in my life and according to them I've owed them money since 2005. It's now 2020! They keep threatening to hand me over and nothing comes of it. I assume they're the reason I now have bad credit. Yet I can't contact them to sort this out. Daily I get sms's and calls. When I try to return calls the numbers don't exist and I can't reply to their sms's. What kind of company are they if so many people are complaining about the same thing? How do you get rid of ******** like them?