OPPO a74 reno. don't buy this phone

I upgraded my cellphone contract at Telekom Kollonade mall. I took the OPPO a74 reno. My biggest mistake ever. Upon using the cellphone whatssap calls and videos are not working at all. I went back to the shop after waiting for 2 hours sales consultants busy acting as if they can fix the problem wasted my time even more. I left the phone at the shop and the manager promised to call me back and explain if they booked the phone for repairs or not. Victoria has not called me yet. The unfortunate part is that I can't cancel because I must pay for the hand set an amount of R12500. Telekom is this how you treat your customers.? I am frustrated with this situation and I am not going to call the shop. I just want to see how she interpret customer service. Nxa no more.