Why do I have a Negative FNB e-wallet balance

FNB has taken my personal e-wallet balance to a negative amount. I tried to withdraw money from my Betway e-wallet which is a separate account from my personal e-wallet, but the transaction failed and I did not receive the money. My personal e-wallet account now has a negative balance while my betway account has reversed the transaction. I have called FNB & the e-wallet department multiple times and written a few emails yet the issue remains unresolved.