Anyone have the GOG cart choke on a payment before? My paypal account was clearly debited on a transaction but my GOG account does not show my games... all my attempts to submit support queries are getting nothing but automated emails. It's frustrating. I have sent info regarding the paypal invoice etc

try this:

https://secure.gog.com/en/account/refresh/

support usually reply within 24 hrs but it might take a bit longer if they're busy - hopefully it shouldn't be too long though, I think account and payment issues are considered high priority

There have been a handful of similar complaints posted here recently, Frag, so you're not alone.

GOG support seems to be well-regarded around here, so you can be confident it'll get sorted. I understand your frustration, though.

Make sure you use the right topic in the support request, as some of them (e.g. Other) are low prioritized.
http://www.gog.com/support/contact/my_orders_and_payments

There was another payment issue today, see here:
http://www.gog.com/forum/general/failed_payment_via_paysafecard_got_charged_no_games
Maybe it's a more general problem, but if so, I'm sure GOG staff is giving their best to solve it.

If you consider how many layers the system has to use, and how many of them could go wrong...

GoG/Site side: Separation of the PHP website and the Database that holds all the information. This includes plenty of issues, like how to handle cookies, sessions, javascript...
Payment system: Gog transfers you to another site to finish your transaction. Well i've used paypal, so i know a bit of their payment system. If all goes well, Paypal sends a receipt to GoG which includes some personal information of yours, as well as how much was sent, code numbers, etc. The transaction number is likely most important along with amount transferred. If that fails to get there (TCP/IP isn't infallible, but it is pretty good).
Paypal: Paypal balance is it's internal management of funds and probably the simplest to handle. However if you don't have the funds, it has to contact a credit card, bank, or other source and do a credit transaction. If there's sufficient delay or refused funds, then that's it's own bit. Don't forget Paypal and other sites also have their own site/database separation as well...
SSL: At any point SSL is probably involved sharing public keys as a outside 'trusted' source. Failing to transfer keys or respond can kill any one of the previously mentioned steps.

If you look at it that way, there's probably a minimum of 7 layers that all have to complete successfully for the system to work. Could be much higher depending on how much background stuff and verification is being done, or other technologies used.

However as long as they can confirm they got money, duplicates can be refunded easily enough... and adjusting a few entries in the DB is all it takes to enable your games, so it's just a matter of filtering through the data...

I had this happen to me for the first time a few days ago, it took them a little while but they did fix it, so I wouldn't worry yet.

Apart from what others have said, this is the weekend. I'd expect no response before the night of the sunday, at best. I had a similar problem with Paypal two weeks ago and it was promptly solved after the weekend.