My sister has been ripped off by EE, is there anything she can do?

So, my sister was paying EE £30 a month for 24 months for an s7 edge and 2gb data.

This ended and she was happy to keep the phone so I told her to get a sim only contract. This is where she messes up....

She went to the EE shop today, signed a 12 month contract (I've got a copy of it right in front of me) and she's now paying them £17 a month for 3gb of data. She thought she was getting a good deal but as everyone on HUKD she's getting royally ripped off.

I've looked online and it says you don't get a 14 day cooling off period if you sign a contract in person?

What's the best course of action?

Thanks everyone