Huawei p30 lite

I bought a Huawei P30 lite at MTN stores for R6300 on the 04/04/19. On July it started having problems when people were calling cannot hear me. On the 24th July I took my phone to the service center (huawei service center Cornubia Mall) and I waited for 2 hours for it to be repaired. After 2hours I was then told the phone cannot be fixed there are no spares they will order. On the 3rd August (after 11 days without my phone) I was told to pick it up. I went to pick it up on the 4th, and today on the 7th August the phone is not working again same problem as before people cannot hear me at all . I bought this phone cash and I bought it because I thought it was good for business as a fashion designer I wanted to invest in a quality phone. I have lost so many customers because now it's like I am not reliable people cannot reach me. Its like I'm running away from them. I don't have money to buy another device as a back up phone at the moment. I need my money back because it's obvious you are failing to rectify this problem or I need another brand new device. I can't work like this.