Polyster Prints - Not exchanging the item

I ordered a combo of two tshirts, order no. #***** on *rd november **** which was delivered on *th november ****. I asked the delivery guy about exchange policy in case of size issue, he said that exchange is possible and that I’ll have to call him. I tried those tshirts and they were small in size so I called the guy. He asked me to call the next morning at **. I called him the next morning he didnt pick up the call. I tried calling him the whole day he didnt answer and then he blocked me. I mailed the site twice but no response from there as well. I whatsapped the guy and he blocked me there too. I havent used the tshirt even once I just want them to get exchanged as they are too small for me also the quality is veryy cheap.