Agree with the up, need to pay attention, but

No need to over react,  seeking med help is definitely recommended, btw, how old is the girl?

Regarding craving for sugar/candy,  I had a similar experience with my younger one, for many years, he craved the sweat and caused me a lot of headaches having to deal with the problems associated with it, such as poor sleeping and a grumpy attitude and hyper activities.  When he was around 8 or 9 years old,  I did take him to see doc as well.  We never gave up helping him,  I think when he was about in junior high, he started to change  and is going to a good university,  in high school he only occasionally gets some ice tea if needed with friends, but most of the time not at all.  So there is hope, do not give up.  I am sure she must be a very smart girl too.     Pls feel free to message me if you want.

Btw, I know a friend's son also just like that too, my experience with them is that, those types of kids are super smart, and may have ADHD, ( or minor at least),  and they body needs to have constant stimulation, and the sugar and temeraly provide that. 

The last thing, regarding the repeat stealing, one needs to look into what is behind her action, not just on the surface level, many ADHD kids  tend to lack impulse control and have lowered executive functioning.  So find a good doctor and ask for professional help.  Here are some readings to help you. 

 https://www.healthyplace.com/blogs/parentingchildwithmentalillness/2017/12/childhood-adhd-and-stealing

Finally, dealing with the lady who lost money, you still want to take full responsibility, she might be wrong with the amount, but no need to question her, just return it all and maybe discuss it with your girl and let her learn to take the consequences.   Depending on her age, always take it seriously, but never think it is the end of the world,  she will improve. 

Remember,  a kid with love,  will never go wrong.