Yours is a multiplexed car. You either need the proper pug towbar ECU, or a relay unit to feed the electrics. If you try to splice into the electrics directly like the olde days then the cars electrical system will probably suffer damage, most likely the sensitive BSI.
Any decent towbar specialist will sort you out, but be warned - it's not a job you want done on the cheap one one of these wee motors. It needs the relay unit, and to properly and safely install it costs what it costs.