Zone Fitness demanding payment from teenagers - who is unemployed

My daughter and Son, unemployed was approached by a consultant from Zone Fitness Promenade 27 Dec 2025. Promoting free month subscription who knows what, uneducated they gave ID and contact numbers etc. Out of the blue we are getting demanding SMS's and calls that fees are behind and never paid and must be paid immediately to avoid being handed over!!! After visiting the branch and making calls to get this sorted, we need to get the messages of the consultant to prove that we did not sign up (who no longer works for them) how do you sign someone up that is unemployed?? Please explain. Do you not do credit checks before signing people up especially from teenagers.