A quick look online says that new pads and discs all round would be about £170 for the parts. You really don't need a Jeep specialist to do the job, there's nothing special about it.
£333 sounds remarkably cheap for a stealership, given that the cost of mopar parts is markedly higher. Still, I'd either do it myself or take it to your local backstreet garage where labour isn't £120 an hour. Ask people you work with for a recommendation.