Payment options not working while purchasing books

I am able to load the page: https://store.raywenderlich.com/products/concurrency-by-tutorials

But when I press “BUY EPUB/PDF $19.99” labeled button then the error happens. Please check the attached Video. Are you having the same problem? I contacted support but no response. Is there someone who can help me out.

Video: Dropbox - File Deleted

@katiecollins Can you please help with this when you get a chance? Thank you - much appreciated! :]

I wanted to buy few books where there were 50% off recently. But due to this payment issue, I couldn’t buy. And the issue still persists, also the 50% off offer gone.
Is there any way i can buy the books on 50% off offer? now?

Hi @partho_biswas I’m sorry you’re having trouble here :[ I believe you’ve had a response from our customer support team and we’re dealing with it along with our payment provider. Hopefully this will be sorted for you very soon :]