Marks and Spencer today bowed to pressure from bigger busted customers to sell larger bras at the same price as smaller ones.
Campaigner Beckie Williams, founder of Facebook group Busts 4 Justice and a 30G herself, was so infuriated by the policy that she bought a share in the company with the intention of confronting chairman Sir Stuart Rose at the next annual meeting in July.
Today she won her battle as Marks and Spencer admitted it had "boobed" and promised one price would fit all from tomorrow.
"We've heard what our customers are telling us that they are unhappy with the pricing on our DD-plus bras and that basically we've boobed.
"So from Saturday May 9 no matter what size you buy, the price is going to be the same.
"We're not going to cut the quality though - they'll still be made to the same high standards so you get the best support on the high street."
From tomorrow, the chain is also offering 25% off the price of any bra in any size. The promotion will last until May 25.
More than 11,000 people joined the Facebook group Busts 4 Justice which said Marks and Spencer was putting a £2 surcharge on bras with a cup size larger than double-D.
Some of the online group's members suggested a boycott of the chain until it revised its pricing policy.
Miss Williams, 26, said M and S had got away with the "unfair" practice for too long and urged it to think again.
The Brighton-based writer called the policy "ridiculous" and bought a £3.40 share so she could put her case in person.
M and S initially told her the extra charge was required to cover the work involved in making larger bras and that customers had said they were "happy to pay a small premium" of between £1.50 and £2 to cover the specialist work needed to ensure a suitable level of support.
On Wednesday, supermarket giant Asda joined the debate by unveiling a £4 bra in cup sizes A to F in its George range.
Fiona Lambert, George's brand director, said: "No one would dream of charging one price for size seven men's socks and a different price for a man with larger feet, so why should they do the same with ladies that are blessed in the chest department?"