Courierit doesn't deliver

I've been waiting since 7 August for Courierit to come pick a parcel they need to take back to adidas. They have never showed up. Today, I eventually got through to adidas offices as Black River Park and told them what was happening. They got back to me, saying that the courier company claims they have been to my place twice but no-one was there.

I have never received an SMS, WhatsApp, email or phone call from the courier company whether before the alleged pick up, while they were allegedly outside my door or after they allegedly had been to my place.

It's frustrating as I simply want to return the 2 items and get my money back. Even emailed Courierit at *** - no reply to my email