Product: Credit card or prepaid card

I was the victim of a scam and feel as though the crdeit card company was complicit in the scheme ( whether knowingly or not. ) The scheme could not have worked without the credit cards process that i find to be at fault.
I was beginning to work for company and as a part of my probationary period I was to make purchases. The first of these purchases were XXXX XXXX Gift Cards. I was to use a credit card that had a high balance on it. The company employing me would make a payment on this balance and then I would use the resulting credit to purchase the XXXX XXXX gift cards.
I used the credit cards mobile app to see when the payments were made, when the credit was available and when the charges for the gift cards would appear on my account.
My starting credit card balance was a little over {$7000.00}.
The company employing me authorized a payment to my credit card on X/XX/17 in the amount of {$4500.00}. When that showed on the credit cards mobile app as available credit on X/XX/2017 ... I used the avaiable credit to buy {$3900.00} in XXXX XXXX  cards.
The company employing me instucted me to make a XXXX XXXX dollar payment to my credit card when the first XXXX XXXX  purchase was applied to my balance. So on XX/XX/2017 I made a {$6100.00} payment from thier bank to my credit card account.
When that payment resulted in the mobile app indicating I had the available credit on X/XX/2017, I purchased another {$6000.00} worth of XXXX XXXX cards.
I waited until the charges for those cards appeared on my credit card mobile app and then as instructed on X/XX/2017 I made another {$6100.00} payment from my employers bank to my credit card.
When that payment showed as available credit on the mobile app on X/XX/2017, I made another purchase of {$6000.00} worth of XXXX XXXX cards as instructed. The alledged employer cashed out the XXXX XXXX Gift Cards before I was aware.
Subsequently the alleged employer reversed all the payments to my credit card and left me with a balance owed of over {$24000.00}!
When I spoke with my credit card company about it they informed me that a bank has 15 days to reverse it 's payment to the credit card.
My question then is why did the credit card company show that the payments were good and therefore I had the credit avaialable. I never would have charged the XXXX XXXX cards had they waited the 15 days to show the credit was available. The payments would have been reversed before then and I would have not had the credit available.
I feel my credit card company aided in this scam by showing available credit when they should not have. I spoke with the credit card company several times and no one could answer my questions about why the available credit showed on my mobile app. They said it was standard procedure to post payments on accounts before the 15 day reversal period is over. How can that be? It would seem that scammers know that! It would even seem that maybe the people pulling off the scam have a very deep knowledge of credit card flaws and how to abuse people using them. The scammers may even be ex credit card company employees ... or current employees!
What matters here is that a flawed policy has left me owing a balance that I will never be able to pay back. If I make minimum payments it would take XXXX years ( I will be XXXX years old. ) Making the minimum payments ... I would pay back over {$61000.00}! It is easy to see that the system allowing credit when it should not be allowed has seriously injured me and my family financially. I am also apply for work for which I need a government license and this may hurt my chances there as well.
All because of a flawed process by the credit card company for which I firmly believe they are liable.