Your skin can definitely get use to all these products, but be careful not to over stimulate your skin. Medical skin care products these days are so well-rounded that you do not always need ten different creams to get the desired results.
A good cleanser, moisturising cream (maybe a serum) and a SPF should do the trick. I would recommend that you visit one of the Skin Renewal Clinic where an experienced therapist can have a look at you routine and products and advise accordingly. You can visit www.skinrenewal.co.za to find a branch closest to you.