After talking to trading standards I was armed with the knowledge that when the shop had given me a till printed out quote for £20.00 for the camera battery we had entered into a legally binding contract.
I was in a strong position and nothing was going to budge me, I also didn't want to let down my backing supporters on this site also. (Gives you all a pat on the back) 
I entered the shop and heard the familiar ladies voice that was on my phone messages, saying that the battery was now going to cost £35.00. She was obviously a real business lady who didn't suffer fools gladly but I had a plan. I quickly headed for the battery display rack in the shop and found the battery I wanted was now in stock but priced at £26.99 so where did this £35.00 pound figure come from, was she going to say that they could knock down the price from £35.00 to £26.00 and think I would go away happy and she would have sold the battery at the normal price. I picked the battery off the rack and took it to her at the till and handed her the quoted receipt at the same time. At this point she realised who I was and started saying that a mistake had been made with the quote and she would see what she could do. But she now new that I could see the normal price was £26.99 and the £35.00 she had mentioned on the phone was no use to her now. Well she huffed and puffed while going in and out of a back room muttering all sorts of stuff under her breath. I think she was trying to think of a way of getting more money out of me but I just stood there and said nothing. After a considerable length of time had passed which was verging on the embarrasing she eventually said begrudgingly, well I suppose I'll have to let you have it at the quoted price as a gesture of good will.
Its amaizing what a bit of eye contact and a face to face meeting can do as I know an over the phone conversation would not have resulted in the same outcome.
She was thrown off her original plan by me picking the battery off the rack clearly showing the shop price was not the £35.00 she mentioned on the phone.
I love it when a plan comes together but I was slightly disappointed that I didn't have to use International rescue, a chieftain tank, or the trading standards referance number and phone number I had in my back pocket.
The lady made it very obvious that she was not happy but collapsed under the look of stealey determination I had on my face. .
Thank you all for your advice, It made a differance to my attitude and the final outcome.
Tony. KOTC would probably say something resembling this now. Go to your local Breathe easy for a little eye contact eh'. King if your out there I hope your feeling better today.
Venting update. 
Update for all interested 
Lung transplant second opinion update.
Dont panic.All I could think of was Corporal Jones.
