it sounds as though the damage may have originally been caused by an attempted theft? someone would swap the car because problems with locks and keys on fiats can be an expensive nightmare if you dont know how to fix it, and people arent very nice in general so they dont care if you get stung. for future reference, before buying a car do some research, a quick look on this forum would have told you to check for a red key and 2 blue keys. you shouldnt buy a brava if it only has one key, but at least you have the most important red key so hope is not lost.
if the steering lock is remaining activated with the key in the ignition it most likely means the barrel has not been fitted correctly or something is broken (the snapped part you have been told about). if it was working and now it isnt then whoever fitted the ignition barrel is to blame. either way this problem can be easily fixed once you identify the broken part and replace it. only buy parts from scrapyards, its much cheaper. a trip to fiat will be a waste of time for problems like this. they'll quote more than the cars worth.
if the code light remains on with the red key its usually a sign that the ecu has lost all blue key codes. this can be caused by many things including driving with the red key, or getting sparks when reconnecting the battery, or repeatedly turning the ignition on and off with the red key, or even hitting the ecu can do it. thats not a problem as you've got no blue keys, and blue keys can be programmed into the ecu anyway. basically all you need to do is:
1. fix steering lock with replacement part from scrapyard
2. buy 2 blue keys off ebay
3. get 2 key blanks cut same as red key
4. fit key blanks onto blue keys
5. program blue keys into ecu using the method i gave earlier
6. enjoy the rewards from your girlfriend
fingers crossed this shouldnt be an expensive or difficult problem to fix. the broken part for the steering lock will most probably be on the igniton barrel, that part will be a fiver if you remove it yourself at a scrapyard. buying 2 blue keys off ebay can be as expensive or cheap as you like. they often go for 99p so keep a look out. getting 2 blanks cut will be cheaper than getting a chipped key because you only need the metal part of the key. worst case it will be 30 quid for the pair. the rest is free so i'd expect you to get all sorted for less than 50 quid. good luck, and let us know if you need any further help. i've seen people with worse key issues than this who lived to drive another day. at least you dont need an ecu, it could be worse