It is such a shame when things like this happen because they are so easily avoided.
You did the right thing though. I remember reading a thread not to long ago about this ridicules story about how some one took this girls ball our of her tank while she was at the vet and beat it up and blah blah blah and then she asked for money. There are people on here all the time that come on here and tell every one what they did wrong and then refuse to listen to the advice and tell us how wrong we all are and they really know what is best.
Any who, long story short alot of people are stupid and do not try to help the animal. You have done every thing you knew how to do. I think it is great that you are trying your best and you are willing to spend the money to help this animal.