FNB fails basic banking criteria and excels at theft.

I have experienced the most serious problem possible in banking, one which undermines the entire concept of banking. I transacted with SPAR using my debit card, the money came off my FNB account, FNB confirm this, the money was not paid to SPAR, I did not receive my weekly shopping as a result. FNB does not answer my emails or get back to me after speaking to various call center staff since offering me a series of reference numbers including a payment ID, which of course are meaningless to the seller that did not receive the funds,:and it's not their problem, they just want payment. Once a bank starts charging you without making payments on your behalf, you have a serious issue on your hand. The fact that the bank is entirely disinterested in the problem can only mean that it's not important or a priority for FNB to fulfil the most basic criteria of banking, and that straight up theft is ok with them. What other conclusion am I to draw?