I think a better question is to ask for recommendations for a good trainer/behaviorist. I don't know anything about Naples, Italy, whether the person you need to find would be considered a trainer or behaviorist.
But, I think that would be my first course of action -- take her to someone experienced with the breed, so they can witness the behavior and interaction between you and the dog, properly diagnose the dog's issue, and develop a plan of attack.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC