Unacceptable service

I wanted to purchase a lawnmower online from a well-known company. The transaction was declined by FNB ***** department as the thought it wasn't me who did the purchase. I confirmed with them that it was me and they then "cleared" the error. I was told to wait three minutes after which I could then go online and complete the purchase. When I went back after a couple of minutes, I got a message that I now had to wait 72 hours. As this is totally unacceptable, I contacted the card division and after talking to several different people, I was told that the error was "cleared", and I could go on with the transaction. Needless to say it is still not cleared, and I have wasted 2 hours without any success. I tried to pay with a different card but got a message that FNB could not verify my information. I have now had it with this unacceptable situation. If it wasn't such a hassle to move to another bank, then I would have done that.