Lying sales person and refuse to do a refund which is within the law

I asked for advice on a specific paintball gun and was told it will shoot 50 rounds on a gas cylinder. The gun misfired from the first day and I took it in less than 10 days later, as we were away.

They tested the gun in store and proved that it misfires. They also validated that the sales person gave me the wrong information, yet refuse to act upon it and do a refund. I must now keep a gun, which will use 3 - 5 times more gas and costs a fortune to use.

They refuse to do a refund and don't care what the Consumer Protection Act says.