Bit of a write-up for fitting the parking sensors for a cost of £16.50p from ebay.
1) First job was to remove the bumper which was really easy.
-Remove the rear diffuser section of the bumper, 1 bolt each side under the trim then slide it out.
-Remove the large torx bolts from underneath securing the bumper on.
-In each rear wheel arch remove the trims that screw to the bumper.
-Slide the bumper off and place face down on some carpet.
2) With the black trims removed using the drill bit supplied drill each trim to line up with the holes in the bumpers.
3) Ensure all the wires are neat and tidy along the back of the bumper then under one of the light clusters drill a hole through the bodywork and feed the wires through. I used the offside cluster.
4) Put the bumper back on and remove rear trims and carpet on the side you fed the wires through.
5) Connect the sensors wires to the module then the ground wire to the ground for the light cluster and the live to the reversing light wire.
6) Last thing is to mount the box of tricks and the beeper behind the carpet so it will all be hidden and look OEM.