I Agree, ths blue screens of death are anything but helpful, I dont recall the last one that was actually antyhing to do with the actual problem! Only this week for example I had one -unmountable_boot_volume - which would indicate, stangely enough that there was a problem with erm, the boot volume but no, all it was was a faulty sound card!
Anyways back to your problem, are you able to boot into safe mode? Maybe a system restore will be of use here.
When you get your pc back from paying £100 (I agree that the price is OTT if no parts are used, I do this for a living and if it came to the shop I would charge about £40+vat - maybe a bit more if I struggled with drivers - sometimes the case, or if I did a home visit it would be done on time + call out. Additional charge if theres loads and loads of stuff to backup from the pc - either way no £100)
When he "clears the memory" does the pc come back all sort of bare with all your programs and documents gone?
Dont be too concered about causing damage to your pc, the only time I have seen any part of a pc damaged (other than physical) is by overclocking and I assume you arnt overclocking.
Since the problem seems to occur only when trying to open AOheL then I would try reinstalling that.
Hope the above makes sence, if not post back.