Merchants banking is ****

Good Day FNB.....So there is something on my app that I don't like at all... So this month I swipe by Spar, Mtn, garage and another place.... All that I paid with money in the bank... But somehow my account go into minut witg 1300 all the above mention stores didn't get they money... But it went of from my account that same day..Why are they doing Merchants banking 5days afterwards...We don't have money to lay in bank, to wait for them to do they Merchants banking..... Please explain me.... Because it's really unnecessary additional monies that I don't have