Is there a warranty? Mine fell apart in wash.

Since I got a second pair not long ago, I still have the slippers in the original packaging. There is a warranty for the materials and/or workmanship for 1 year. So if you washed them according to the directions on the package, you can send them back to Istoner with $5 and they will replace them with the same or comparable product. I have washed Isotoner slippers before in my washer with other items (versus alone in a big washer) and they have been fine. They washed nicely and I let them air dry on top of my dryer. You can probaby get Isotoner's address on their website.

How do I select the narrow width that is offered?

There isn’t any narrow which is a problem because they have added memory foam and it makes it uncomfortable as your toes go to the end of the slipper. I tried the next size up and my foot slides to the front again and then slides left and right because it’s too large. I bought these for decades and like most stuff these days they are not for narrow feet.

I need to change the shipping address and the order to a gift receipt. How do I do that?

I only did that once and I believe if you go into your account settings you can add a additional address, check that address for your delivery order. The only other way I can think of is cancel the order and re-order it AFTER you added another address