Anyone buying from Auction needs to check the fees before they bid and work out what your bid will cost. Typically they are between 28% and 35% depending on auctioneer.
As for posting, you aren't just paying the cost of postage, you are paying for the time it takes an employee to get the item, package it, address it, get the postage sorted and dispatch it. Employees cost a lot of money to employ. Most auctioneers use external packaging and posting companies, they will have cost you kore than £20 + vat. I just paid £40 for an item to be collected, packaged and posted.
VAT is VAT, they can't not charge it.
As for if the item works, it's a case of caveat emptor. If it is misdescribed then you have recourse, but buying unseen from auction, you pay your money, you take you chance.
Have you been ripped off?
No - you just failed to read the small print before bidding. We've all done it.