Incorrect instructions on medication

I went to clicks in brackenhurst on 09/11/2017 to fill a prescription and although i was given the correct medication the instruction on the dosage was wrong and was not even in my name. I got two boxes of the same medication, one had my name on it and the correct dosage and the other was made out to a totally diffrent person and with a very weaker dosage and as i started out with the weaker dosage, i became sick because i was not taking the right dosage. I only became aware later that it was incorrect and i tried to phone clicks and they did not answer. I am really disappointed.