Calmly explain (via an attorney) that you want your shares back, and any legal fees/expenses involved. I wouldn’t care where they get those shares (IOW, they can buy you ‘new’ ones and let their mistake stand), but you want them replaced.
If the price of the borrowed shares goes above the price they were at, you can be damn sure the brokerage will come to you demanding the shares, or the money to buy them right then on the open market. No matter what the price went up to, you've gotta pony up, or else they come after you with guns blazing. That's a big reason why people tried to fly off skyscrapers back in 1929. Some checked out back in 2008, although I don't think any did it by taking the big dive.
So the brokerage just reversed the situation. In effect, they borrowed the shares from you and loaned them to someone else. They've got to get your shares back one way or the other, just like they'd make you do if you were the borrower in a short squeeze.