Poor Quality, poor customer service

I purchased a duvet set for my son's for his birthday in December 2020, after using it for 2 weeks, the seam has split, which I was not impressed with. How will the set look after a year? I got no response from their customer care on their website and initially a response from their facebook messenger, but now no one is getting back to me. I do not have the slip, as my son liked the colours of the duvet and it fitted the bed well, so I thought there was no need to keep the slip. I have however sent them a screenshot of the purchase on my credit card, and this was the only item purchased at the time, after this screen shot, no one has responded. If you are not going to replace or fix the set, let me know, do not leave me hanging.