Unhappy customer

I ordered two kids tablets from them on 10 March. Within in 2 days my kids complained that the tablets batteries don't last, it freezes, charger point slips out and downloads cant be done. I requested for the tablets to be collected, which was only done on 26 March. For almost 2 and a half weeks I have been begging them for my refund of R1600. If I don't phone, they don't phone me back. They pass the bucket from one person to the other. I have never had such bad service. I demand my money back before the end of this day.