Lifestyle legal's issues

Hi my name is Philip Lambrechts. A week ago I recieved an sms from lifestyle legal stating that I owe them R1838.72 without a reason,further stating in the sms that I will be blacklisted by transunion. They are not responding to my e-mail nor my calls. About 2-3 months back I had an issue with capitec bank which was resolved resently. The time I was was in contact with transunion they assured me that my credit record was clean and sent me a credit report. So if lifestyle legal is claiming that I owe someone an amount of R1838.72 which they cant tell me because they dont answer me then how did transunion and the bank misslook this matter. I would just like to know to whom I owe that amount to and what for. Please assist me in resolving this matter because this is truely unprofessional and unacceptable.