Vodacom Chatz Dainfern Square- Oppo device

On 23rd January I signed for a Vodacom contract package. The male sales consultant advised me that the Oppo brand was a good alternative to Huawei as Oppo has inbuilt android, allowing access to Google play store. The consultant reassured me that Oppo is a good brand and he had sold 9 mobile devices just that month with no returns or customer complaints. When I received the Oppo mobile device the device kept freezing. When I took the device to Vodacom repair store , it was replaced with a brand new device of the same model. The replacement device had exact same problem so I returned it to Vodacom repair store, where the consultant advised me that chances are they would replace it with another brand new device which will probably have the same issue and wouldn't be repairable as Vodacom does not yet have the software to repair Oppo devices. This back and forth has been on going since January and do date I am paying for a device that is sitting at the Vodacom repair store. I just want a device that works. Vodacom please intervene.