Blocking account no contact

I went went to make a purchase at the mall of the south, only to get to the till and the cashier tells me my card is blocked, which I was advised to go to customer services, which they asked me when last did I used the card to purchase and I responded on Sunday, and they asked how much, which I did advise them. The lady tried calling to have my card unblocked but there was no one at the office to assist, and the lady advised that they only block cards when they can't get hold of the client but I was never contacted. I couldn't make a purchase of what I have required, no I must travel up and down to make a purchase. This is really ridiculous that there is no body to assist at the head office when stores have extended trading hour.