Second Hand Brompton Causing Me Grief

[theposhbarista]

2002 model M3L purchased for around £300 5 months ago from an owner who clearly didn't give half a toss about his Brompton- as a complete newbie cyclist at the time I failed to notice, amongst other things, the lack of a suspension bung, horrific damage to the rear triangle, the fact that the oaf had been riding around with a heavy lock on the handlebars and the fact that it clearly hadn't been serviced once since it was bought new. So far:

• New brake cables- one of them snapped while riding!
• New mudguards- old ones shattered
• New handlebar- scary dents (previous owner decided to use it as a lock holder)
• Complete overhaul of the rear triangle- huge hole where the bung was meant to go - but according to the mechanics 'it may not last much longer'
• Missing components- I seem to discover these on a monthly basis when things go wrong

I don't tend to try and meddle with servicing myself- the best I've ever done is refit the chain with kitchen gloves- but no amount of money or expert help seems to be able to put this Brompton right (as in, make it ride at least reasonably close to a used Brompton). Am I being unrealistic with my expectation to be able to revitalize this machine, or is it time to give up on this terribly abused bike? If this goes on any much longer I will have spent nearly as much as it would cost to buy a regular M3L from Evans.......