He wont last long. Fifteen quid! Should have sent you packing for a couple of hours and on your return told you it needed a new Flux Capacitor. £199.99.
I don't know much about Flux Capacitors but if he'd suggested that I needed one fitting he would have been advised to put it somewhere where the light rarely shines and not in my Computer.
We've used the shop for some years now, they sell reconditioned PCs and Laptops at a reasonable price (£45 upward - with 6 month guarantees), and good customer service is what helps keep them in business.
Old fashioned business practises do work sometimes.