If you received the incorrect item, you needed to start a return choosing the reason 'item not as described'. Private sellers can not refuse those returns.

If you chose a 'change of mind' reason, such as 'wrong size/doesn't fit', a seller registered as a private seller could refuse the refund.

Obviously I can't see who the seller is, but having a shop, 44 items for sale, and a healthy selling record don't necessarily indicate a business seller.

Ebay don't have a specific, easy way to report your suspicions about an account and they tend not to act on such reports anyway.

(I don't think this is defensible, but it is the reality here.)

Try your payment provider for a chargeback. You have bought an item online which was 'not as described' so you do have consumer rights and that is the best route for you.

All accounts have to display if they are private or business.

I always check and I would not buy anything new from a private seller, especially if they clearly have large stocks of different items, hundreds of clothing items in different sizes, brand new cosmetics, health supplements etc.

Doing your own 'due diligence is more effective than trying to get Ebay to act on this issue.