take it this maybe the part you need
http://cgi.ebay.co.uk/ROVER-75-MG-ZT...item2558acc48e
You could actually change the bush and complete lower arm
http://cgi.ebay.co.uk/ROVER-75-MG-ZT...item45f3150899
bulbs are preety easy to change and a 5 minute DIY job i take it the garage is chargeing near £130 an hour labour charges as i would have thought theres no more than an hours work maximum with a ramp and garage equipment available