Price increase of 50% above qouted price

After listening to promo of company on Heart FM, I decided to give them a try as I needed to service my Chev Captiva. Went round to branch and got quote and subsequently arranged for the service. Took the vehicle in and received a call from a lady whose name I cannot recall. She confirmed with me the price which was in the same ball park as the quote and I gave the go ahead for the service to be done. Close to the end of the day I phoned to check if the car was done and was informed that I can collect after four but also that the \plugs cost a bit more". I was not offered the price increase and neither asked because how much of a price difference could there be - R100.00"