In liquidating debit cards, I have used several of the IRS payment options. For payusatax.com, I noticed that a payment I made (which the site had confirmed) wasn't showing on my IRS payment received page. So I contacted payusatax.com by email and the payment disappeared from the website's list of my payments (though I have a printout). Then I tried to call and email customer service with no one answering or responding. So as of now I am out 500 with no customer service contact.

Update: And after waiting 1:15 hours on hold- they disconnect me.