Nope
In a word, no.
Without the red key, u cannot make copies of the key or do anything 2 the ECU. Fiat will charge £1000+ to replace the system and give u a new red key and 2 new blue 1's.
If the garage lost it, they r legally responsible and should replace it free of charge 2 u. What would happen if they called u and said "Sorry mate, we lost ur engine" ?? If it's not a Fiat dealer, i'd even consider reporting it 2 the police if u have no joy as once they have that key they can steal ur car with consumate ease. If it is a Fiat dealer, i imagine they would have offered 2 replace it free of charge anyway, as they know the importance of the red key.
If it is a Fiat dealer and u get no joy, threaten legal action and contact Fiat UK in Slough and report them. Fiat r **** hot on customer service in my experience. A formal letter from urself, or better still, a solicitor, will help.
Good Luck,
Roberto.