Two days later, I got this response:
Thanks Linda for contacting Pampers.
I am sorry that the box of diapers you purchased had the wrong size of diapers in the package. I understand how frustrating that can be.
Our goal is to produce high quality products that consistently delight our consumers and I'm sorry this wasn't your experience. Please be assured I'm sharing your comments with the rest of our team.
Since your satisfaction means a great deal to us, I'm sending four $10 off coupons by postal mail, which will be good towards your next purchases of any size or version of our Pampers diapers. You should receive my letter within the next 2-3 weeks.
Thanks again for writing.
One more reason to love Pampers. They don't leak (on my kids), have great coupons, and apparently have pretty awesome customer service.
And, sometimes it pays to send an email.