Takealot exchange delivery not done

Good day

I need help with my order ***2

I bought a cover for my cellphone I didn't like the colour I asked take alot to exchange the cover from gray to black..on the package I was exchanging I also added 2 other items I was returning headphones and earbuds ..asked the driver if it was okay to put everything in one box..he said it's okay.. a few days later I got a refund for the other items..and received a message on the 18Aug to say they delivered the replacement and I signed for it... I never received the replacement item. Logged a couple of calls to take alot all the agents promise to look in to the matter and get back to me.. Till today I'm still waiting .. I still haven't received the item.. Please assist me