I tried to buy some bitcoins from a popular/trusted website
the payments had charged from my card , and my bank support told me : the purchase done successfully
but the website system released this message : failed to charge the card
the website support told me that they did not take any payments and their explanation
Visa is a middle man , it takes the payments and check some conditions
if the conditions as expected , it will send the payments for them
if not , it return the payments for me in a few days
2 days passed and I did not take back my money
I don't want to mention the website name , I'll do it only in case I really stolen
I suggest that you show some proof of payment to the support. If they refuse to pay , they are probably scammers...
However, you need to be sure you actually paid. Sometimes a visa authorization may look like a payment is not
If you give us the name of the service, it would probably help, as kakmark said.
There are some legit websites such as coinmama and cex.io that allow you to buy with credit card.