Freelander 2 tow bar / warranty

[[AJ]]

I bought my wife a Freelander 2 HSE (which I actually like more that I thought I would) and want to fit a tow bar for use with a Thule bike rack. LR want £830 for fitting a quick release tow bar with electrics which I thought was rather shocking! Does fitting a 3rd party bar and electrics effect the vehicle warranty? If not, does anyone have any recommendations for a quick release bar?