Yes, it is an unfair and deceptive trade practice to advertise one price and then charge another. See my 93A guide for information on how to write a demand letter. You should be refunded $2 which is a little less than the cost of the certified letter you will need to send.
My answers are general in nature based upon very short, and often incomplete questions. Please do not rely upon my answers. If you need a legal opinion, you need to hire a lawyer who will take the time to fully understand your problem and then take the time to research the issues.
Hope the pizza was good...
It sounds like this shop might be skirting the edges of what is permissible under MA consumer protection law, but you might pay more in heartburn than you will collect unless you are careful. It might be that they are just sloppy or informal in the way they price pizza pies.
Technically, section 940 Code of Mass. Regulations 3.04 from the MA attorney general's office calls for greater exactitude in pricing, as inaccuracies that redound to the favor of the merchant could be interpreted as deceptive and a violation of Mass. Consumer Protection law. The regulations says, " No claim or ... shall be made ... which has the ... tendency ... of deceiving buyers ... as to the ... usual price of a product, ... or any saving relating to a product."
Consider buying from another pizza shop and letting this shop know the reason why. Good luck.
This response is intended to provide general information, but not legal advice. The response may be different if there are other or different facts than those included in the original question. My answers are general in nature and based upon very terse and often incomplete information. Please do not rely upon my answers. If you need a legal opinion, you need to hire a lawyer who will take the time to fully understand your problem and research the issues. This communication through a public website is not privileged or confidential and does not create an attorney-client relationship.