If I never bought a stamp for a letter in 2 or so years, then needed to, so went into the post office to buy a stamp and found out the cost of a stamp is 70c instead of 45c I paid last time... is it the PO Office's fault I didn't know that? Having a little tanty at the counter about the cost of stamps wouldn't impress the staff or other customers and I would still have to hand over 70c if I wanted to post that letter.