unprofessional on delivering classes

I've been going to virgin active rooishuikraal for over a year now, now they have classes for zumba however the zumba instructor giving classes on Monday and Tuesday is almost always never there, there is only 4 zumba/just dance classes a week and unfortunately I do miss the Wednesday class due to work , I go every Saturday and the instructor for Wednesday and Saturdays is dedicated and always on time, since last year the lady who does Monday and Tuesday is either on leave which she was on over a mth from dec to 22/01/2018, now since last week she has been through only last Tuesday.then you get there and they cannot even substitute her with a zumba instructor but gets a move class with a guy , the club manager says she has personal issues however this pathetic service has been ongoing and by now knowing how unrealiable she is why not get another instructor??? the manager's answer is zumba instructors are hard to find ? so the entire of centurion you'll cant find someone else dedicated ??? no man this is not good service and im tired of the excuses that you'll cant find someone to totally replace her!!! we go there to detress , find someone who is dedicated we cant be having different instructor's every week and the manager knows she wont be in for the nxt few weeks on Mondays due to her personal issues , is he just keeping her spot available and not wanting to replace her??? no man this is really unprofessional and virgin active brand is getting tarnished due to that one unreliable instructor!