Dhamah, sounds like you've royally screwed, not by Alfa tho'.
2 years, 100k miles is heavy duty mileage.
Did you buy from a trader with no warranty?
Did you have the car checked by AA, RAC first?
Do you have legal cover with anyone (car insurance, house insurance etc.)?
If not, you will be lucky to get a goodwill gesture from Alfa (free labour maybe!!)
The trader, if they are kosher, may be legally responsible, if you can prove they knew about impending failure.
Good luck, tough lesson. Don't blame Alfa tho' - remember that the car may have been serviced, but was it looked after?