They sell goods that will require repairs after a month of being bought

For the second time we had to buy from cash crusaders amanzimtoti in Andrew Zondo. The worst ever, never buy anything from them. We first bought a laptop in Feb for my son's school. Within a month they it wasn't functioning and said we should bring it in for repairs, no option of changing it or maybe them suggesting to give something else in the meantime. Now a month ago we bought an iPhone for R4000. Same thing, it went blank and they suggested we bring it in for repairs. And looking at the sequence, you buy and within a month you have to bring in for repairs. Are these things tested or waiting for us bring back for repairs in after buying them? This is a rip-off, you guys are selling us things that are not in the right standards even though they are second hands. Please commit in doing due diligence before you **** us. When can I get the phone back as it is being used for school work? And your phones are forever unavailable or offline