Poor customer service

I bought a track pant online adidas on the 6th October 2020 and it was big. On the 10th October 2020 I requested a return and I was told its going to be collected on the 12th October 2020. Till to date its not been collected. I've been writing emails reminding them making calls every week. I've calling the whole of this week,they are promising to get back to for the arrangement of the courier. I'm still to call me and tell me when is the courier coming to collect. I've been waiting for a month now.