DEBITS ORDERS PAID AND THEN UNPAID - MONEY IS OUT OF THE ACCOUNT WITH NO EXPLANATION.

I am so sick of FNB and my debit orders being unsuccessful when there has been sufficient funds in my account. All my debit orders where received and then i receive emails a day later stating that it was unsuccessful.What irritates me as that the money was taken out of my bank account yet the debit is unpaid.So where is that unpaid debit money because it was certainly not paid into my bank account by FNB. I want my unsuccessful debit fee to be paid back into my account and i want an explanation as to what happened to the money that went out of my account when the debit was successfully received. FNB has ********** transactions happening right under their noses then they want to make it seem as if the client is wrong.I want my money refunded back into my account or i will be taking my business elsewhere........