solutio indebiti

at around 10 am on jan 3, 2012 i went to a lab for some exams. i brought p2000 because i was actually thinking of getting the p1300 package. my fees totaled p820, so i gave the secretary/receptionist p1000. she gave back my change. however, when i stood up so i could transfer to the extraction corner, i saw a rolled p1000 in front of me. i was in a hurry and not feeling well at that time. not thinking it was my money, i gave it to the secretary/receptionist thinking that she forgot to put the money in the drawer. she readily accepted it. i only found out that i lost my P1000 in the afternoon of that day. i called our helper to go to the lab and ask for the p1000. the secretary/receptionist said that she received P1000 only. i went to her the next day and demanded the return of my money but she refused and denied having received twice from me.

can i sue her for unjust enrichment? the lab does not have cctv camera that can prove that i did hand her the 2nd p1000.

actually, i'd say it's estafa but its going to be tough to prove with only your word

thank you for replying, atty. i did consider it was estafa. you are right, I really do not have any evidence that could establish her guilt beyond reasonable doubt if i were to push through with the criminal case. that is why i am banking on the civil case of unjust enrichment instead.

small claims case then, rules on sc.judiciary.gov.ph