My Dad has now finally managed to smash it off properly. Been trying to bodge it back together this morning ready for Mallory tomorrow, but it looks a right dog's breakfast... 
Phoned Mr T to get prices for new ones and had a right shock:
Right hand side: 76851-17901
£66.29 + VAT 
Left hand side: 76852-17901
£69.77 + VAT Despite arguing with the woman about it being only a bit of plastic the price didn't change!
Anyone know if anyone else supplies them and if so, how much?
Alternatively anyone got some spares in reasonable condition they want to sell me?
Tom