Ineffecient Service Provider

I took my son to eyes@work sometime last year for his eye test and new spectacles. all went well with the testing. the optometrist then recommended that he start using contacts since he is now older. she went on to say they will give him a pair to trial for a month after which he will advise which one he is comfortable with so that they can place an order for him. they will then give him to use for 6 months. I then asked her if there was a cost attached to that and she said No it is for trial basis they will only charge us once he is happy with the 6 month trial when he decides to use them to which I agreed and my son also agreed. after his matric exams I took him there again and he was given the 1 month trial for free and we were charged R250 admin fee(which we were never advised of previously and I paid) we then contacted them for the 6 months supply and we were then told that we have to pay for the order. when I asked what changed from what we were previously told to which my son also attested, we were told that it must have been a misunderstanding. I asked how can 2 people misunderstand the same information on 2 separate occasions the optometrist could not answer. she kept on saying we must have misunderstood her. I asked her to ask her boss (the owner Lynette to please give me a call to this day I am still waiting for the call. I feel that my son and I were treated unfairly. I then asked her if this was a race issue because English not being my mother tongue or first language I must have misunderstood her.