Bad service and problem not yet solved!!!!

We had something interesting that happened with us yesterday at wiesenhof inside sandton hospital, We had lunch then when i had to pay my card showed declined, So the waiter tried again and the same thing happened, I then went on to my phone banking and on my statement it showed the amount did went of, I then spoke to the manager who said this is a thing that happens a lot because there is sometimes no signal, Then i told the manager the money went of on my bank account but he said he had no proof on his side that this money came in on their system, Then i needed to pay cash but while this was going on the waiter that assisted us told the other waiters something and everyone was laughing and gossiping about us. My question is the following, If something like this happens and the money go out of your bank account then it means that the bill is paid, But now they refused because there was no slip and i needed to pay cash, Then this mean that i actually paid double because it is now a day after and that money that went of is not back in to my account so i paid double.. In my eyes someone pockets this money and in my eyes it's *****.. I want feedback regarding this matter and i want feedback on how i will get my money back. I will never support this restaurant ever again because of this and the manager that didn't actually knew how to solve this problem..