I’d suggest a 100% money-back guarantee with the return of the pizza. The return of the pizza is required to stop the scammers calling 3 days later about their “bad” pizza. If you have to send a driver back to the house to refund their money and collect the pizza, do it. Refund the delivery fee and everything. You gave them a product they are not happy with and should bear all the costs. I HATE warranties where I have to ship the defective item back on my dime.
This guarantee assures customers that they will get a quality product at a fair price. It’s not their fault if they don’t like the product you provide, and the risk shouldn’t be theirs. A good restaurant will allow you to send back food that is exactly what you ordered but not what you care for. You should be that good restaurant. If the product is wrong because of your fault, then try to replace the product. If the product is “wrong” because they don’t like your sauce or crust or “doesn’t taste like Pizza Hut”, that’s a taste issue and you should guarantee a taste that the customer will enjoy (though there will be some that don’t enjoy the taste for whatever reason).
This is YOUR opportunity to say “no risk” to the customer. The only thing they lose is time.