Brace yourselves. A wall of text is coming.
Wishbone: I think the main problem with customer support here is that it is unstable. When it's good, it's REALLY good. When it's bad, it just isn't there.
In the beginning, customer support here was absolutely fantastic, but then the customer base was tiny compared to what it is now. Sometimes it seems that GOG really hasn't scaled up the support department along with the size of the games catalog and the customer base.
As far as I can tell from our logs, it's been a long while since you last contacted us, though I understand that you're basing your opinion on other forumites' experiences. Trust me when I say that we have, in fact, scaled up considerably. :)
Wishbone: Still, there have also been numerous cases where people have not had a reply from support for weeks or even months after they posted their tickets.
However, when the problem is related to payments, GOG is usually very quick about getting it fixed.
Nobody's perfect, and while there must have been many such cases over the scope of 5 years (linkedIn recently told me that's how long I work here:O), but I would say that the percentage of these is really tiny, compared to tons of regular tickets.
There will always be cases when we can't reply for a week or two, if the case is exceptionally convoluted, like when the answer involves multiple departments, or legal stuff, or if we have to wait for a developer's or publisher's response. The best thing to do in such situations is to tell a user that it might take a long time to get an answer, but on the other hand we can't always be sure IF we can get an answer in the end.
I'd say 90% of account- and order-related tickets are pretty straightforward, and also the most time-sensitive ("I can't log in", "I paid but got no game", "I got charged X times too many"), which is why they're generally the quickest to get resolved.
If someone doesn't get an answer for months, then the ticket definitely fell through the cracks at some point - there may have been some unknown glitch on our support system's end, but we should be able to dig it up from the mail server if someone lets us know that there is such a ticket to look for.
I would say that if someone doesn't get a reply in two weeks, then he/she should send me a PM, or open a new ticket, as something really unusual must have happened.