Exchange of clothes

I had a birthday birthday party for my son and received gifts for his birthday. We got gifted with clothes and now we can’t exchange the sizes of the clothes as we don’t have receipts. These gifts came from different people. We don’t know who bought the gifts in the first place so now we are stuck with clothes we can’t use. What should we do? We have tried going to 3 different PEPs and all we get is attitude and no one is willing to help. I am so disappointed in your system and how unhelpful your stuff has been. All we get is attitude. Is this how you treat people? What am i supposed to do with all these clothes.