Micro derma ruin my skin

Hi peter i did a Treatment MesoTherapy which was recommended by the specialist, i was advised to pay for a package of 4 sessions for R4500, i did my first session and had a very bad reaction on my thighs, the treatment is meant to treat hyper***mentation but instead it caused dark marks which looks like burn scars , im disappointed and not wish to continue but they refusing to give my money back and claiming i have a skin condition that why it reacted that way which is not true, i believe that they were unprofessional and dont wish to deal with them again, Peter please help me get my money back