Sell refurbished mobile phones

I would Like to complain about Ackerman's in addeley street ba*****t were my min purchased two mobile phones and both phones are having problems and we took both phones back to the store only to be told that there is nothing wrong but mean while both phones are experiencing battery issues and the one phone is freezing n a warning message pops up CPU level high . please assis because we can not use the phones and they refuse to refund my Mon n we paind over R700 for the devices and it seems like our money has gone to waste on broken handsets that Ackerman's sell if this does not get seen to asap I will take it further