"We boobed," screamed a full-page Marks & Spencer ad, which appeared in British newspapers Friday.

Marks & Spencer gave in to campaigners who argued that the higher prices of the bigger bras was unfair. The retailer charged as much as £2 ($3) more for all sizes DD and up.

"It's true that our fantastic quality larger bras cost more money to make, and we felt it was right to reflect this in the prices we charged," the ad said. "Well, we were wrong."

It follows a nearly year-long campaign by members of the Facebook group Busts 4 Justice.

The women behind the site argued other chain retailers didn't charge extra for bigger sizes, so Marks & Spencer shouldn't, either. And it pointed out that the store doesn't charge extra for larger sizes of clothing, so it shouldn't charge more for larger undergarments.