Faulty parts.

I bought al my spares to recondition my Nissan 1400 engin. All was fine till i started my engin and noticed that there is no oil pressure. I removed the oil pump and fitted my old pump and had oil pressure. I tool the new pump back to Alert for a refund and told them that the oil pump is not pumping. They then said that they need to send it to their technitians to check it. After 2 days i went back to Alert for my refund and they said that it was back from testing and is working fine. I told the sales person that my old pump is in my bakkie and is working fine and i want a refund but it was refused and was given back the faulty pump. At least i have a R353-50 ornament. I will never buy any parts from Alert aspecially an oil pump.