Never had worse service

We bought 2 pitbikes and a quad bike from them and the bikes are falling apart and breaking all the time ever since we had them and they are brand new! Since the 1st week we wanted our money back because the one pitbike don't want to start the other can't idle, the one pitbike's exhaust fell off, they don't want to select gears, leaking oil like mad, their brakes doesn't work and the quad bike's seat fell off and also can't idle ect.. We were suppose to get helmets with the delivery of the bikes and still haven't received such. The quad bike's petrol tank is leaking and the wheel alignment is so bad. Everytime we ask to have our money back and they should take their bikes they say we must bring the bikes to their shop they will fix them. We don't want to take the bikes there every 2nd day, we want our money back. I cannot struggle like this with brand new stuff and have the worst aftermarket service ever!