Hello and welcome to AcmeCorp, how can I help you today?
Hi. I'm trying to buy something but my credit card won't go through
I'm sorry to hear that, so you're getting an invalid credit card error, I'll be happy to help you fix that. First, can I have you log out / log in and try your credit card again on the site.
hm, that didn't work
Okay.  Next, can I have the expiration date of your credit card, sometimes an expired card can trigger the error.
Ah, yes it was expired, oops I'll try another one then
Yes, another one should be able to work.  I'm happy we got this resolved.  Is there anything else I can help you with today?
No, thanks
You're so welcome, hope you have a nice day!