Wells Fargo Bank Account Or Service Complaint

Wells Fargo Bank account or service department,

Other bank product/service Using a debit or ATM card Georgia

I advised grand daughter that I may have a available balance on my debit card for a purchase. If not the purchase would be declined. She was able to make - purchases and accrue up to - in over draft fees. When I called Wells Fargo about the transactions I was informed, because you are a good customer we approved the transactions. I feel violated. IS THIS LEGAL?????