Defective Phone

I got a contract with vodacom around the end of August for the iPhone 7 Plus. Everything went well and they charged me for the device in an efficient manner except they'd given me a Defective model, yes they sold me a broken phone. So I took it back to them, and they did an OBF review, saying I will get a replacement phone. 4 weeks later still no phone. I call and all they say is it's on back order. Why was I charged when they've had the phone longer than I have? If I knew It's be the end of September and I wouldn't have a phone I could have waited for the iPhone 8. Truly poor service. As of today, I was still assured I'd get it today but it should be no shocker that Vodacom still doesn't have stock. They just want to charge you and never actually do what they're paid for. Despicable service. I will be seeking legal action as you readily deducted money for selling me a broken phone and almost a month later are still lazily unsure of when you will receive stock.