With the negative changes that Citi is making to their "sponsored" Costco credit cards -- complain to Costco. Tell them that your consumer benefits are being taken away by Citi. Urge them to switch away from Citi to another card provider, like they last did dumping American Express for Citi Visa.

I guarantee that Citi will get the message. Costco is a huge revenue stream for them, they cannot afford to lose it. But Costco needs to be pushed to do the right thing for their customers - they loath 'rocking the boat'.