********** Debt Collection by an *********** company

I received an sms telling me I have a "debt" with Zone Fitness gym (which I have never signed a membership with) and they have sold the "debt" to Nimble Collection Services for collection. When I check my credit report there is a *** of Nimble Group saying that they are still tracing me and I have tried several times to call them to no avail. What kind of company are you that doesn't verify information you get about people? Also, ask the client of yours ( Zone Fitness) what kind of products or services they provided me with that I have failed to do. Moreover, ask them how did they get my personal details, was an ID presented when that supposedly "membership"was signed. I bet their agents got them **********ly to meet their sales target. Please sort this out quickly because it's affecting my credit record. In case you want something like reference, this is the number *** that is in your *** on my credit record.