£25 for rear number plate bulbs? Fella seen you coming.
Buy the bulbs off ebay, I cant remember the excat size now but £5 should easily cover the cost - just checked:
http://www.ebay.co.uk/itm/2PCS-3-SMD...item3ccd59f62f
Open the boot up, take a small flat head screw driver and slide the units left (IIRC) and then switch the bulb out put the light back in. Simplez.