Billed for returned sneakers

I bought sneakers for my son online December and i ask them to deliver them to one of their stores in Limpopo Thohoyandou, but unfortunate i was not granted leave at work so i didn't go home December i end-up buying sneakers on cash. i spoke to online department since January 2018 they went and collect it and send me an email regard the collection they made, but am still getting phone calls and emails and am afraid i will have a bed payment record very soon if someone doesn't help with this. i was a loyal customers paying my account ontime every month but now after these experience i just want it to be fixed and close my account with them