Mobicel complaint

I bought a mobicel cellphone at ackermans and within one month it was not working anymore, I returned the cell phone and it was replaced after 3weeks then it lasted for another month and again it hasn't been working, took the phone back at ackermans and I received a poor service as they couldent help me, I was told to come during the week and not on weekend, I told them it was impossible to come during the week as I do not have leave days, till today the problem is not sorted. am stuck with a phone that is not working and my money was taken by ackermans for a phone that is not working.