Keeping my money

This is the third time that Woolworths online puts a hold on my bank account for an amount and then processes another amount and does not release the hold amount. The hold amount is R4552. 63 this is money needed urgently right now. Seems Woolworths does this all the time. And then I have to make phonecalls and battle with Woolworths to release MY money. Thus service is terrible. Extremely *********** way of running a business I must say. Is this shop only meant for people who find over R4000 not a biggy. I need my money back right NOW!!