Faulty Alternator remains not refunded

I’ve bought a alternator from the said business. After a week it became extremely noisy even though it still charged the battery. I removed the unit and took it back on 25 November 2017. A redund/exchange wasn’t done reason being it should first be tested in Jhb. I bought another unit which is totally fine because I couldn’t do without one, they promised me a refund in a couple of days but after 2 weeks and 2 phone calls, I only get promises. Suppose this is what happens if one deal with smaller companies without a proper refund/Guarantee policy!