video rental wrong!

we rented to DVD's(what we thought to be DVD's) They were in that section of the store. When we got them home and tried to play them they would not work. We took them back and the store told us they were CD-ROMs. They would not give us our money back or exchange. We rented and returned them in less than 30 minutes. Their shelving was misleading and cost us money. what can be done.

Send the store manager a certified letter explaining what happened and copy the State Consumer Protection Office and the BBB.