If this is possible to get money back for itema bought without sending the parts back is this wrong
Yes, this is possible. The buyer's credit or debit card issuer can issue a chargeback for their payment to be refunded. This doesn't involve the return of the item. This has nothing to do with eBay's own money back guarantee, which does normally require the item to be returned.
The only reason eBay is involved is that eBay's managed payments system means that buyers pay eBay, not the seller. Therefore the chargeback is also issued against eBay - which repays the card company, and charges the seller for this, plus an admin charge.
In some circumstances eBay will indemnify the seller, but not where the chargeback claims that the item was not as described.
Buyers today have multiple rights to claim refunds, if not from eBay, then from PayPal or their payment provider. This is just one of the many risks of selling on eBay.