What actions can I take on this?

ok so today I went to a local shop owned by pakistans. I bought a can of coke zero and it wasnt till i got out of the shop I noticed it had in big writing around the rim MULTIPACK CAN and on the back it said multipack can not for resale. he was charging 69p for this also! I couldnt go back as it was time to go back to school. what actions can i take on this? what would be done?