After almost a decade of being on GoG I need to use their support system thanks to some of these sherlock holmes games having a mind of their own regarding graphics settings.
Do the questions and your information stay within GoG or is part of it outsourced.
GOG handles their own support internally. Support is available 7 days a week however on weekends they have less people available in support, so certain more technical issues may wait until a business week day. Their business hours are in the Polish time zone also, so request that are outside of that may wait until the next business day.
Unlike most stores, GOG provides direct support for the games they sell including installation and configuration, working around glitches etc. However since they are not the developer of the games, if a game has bugs in it that requires the developer to fix them, there isn't much GOG can do about that. They will try to find workarounds when possible, but if a bug can't be worked around then you have to go to the publisher or developer directly as they're the only one who can genuinely fix the problem.
For much older games which are supplied as-is by the publisher, such as old DOS games, etc. GOG does have engineers who try to hack the games to get them to work to a certain extent, but they can't perform miracles without the full source code of the games either, and they don't have that. Their hacks generally are limited to bypassing ancient DRM and trying to get the game to actually run on modern systems. They do not generally try to binary hack games to fix game engine bugs or similar. If there are fan made bugfixes out there, they may include them if the publisher gives them the ok however.
All in all, GOG support and engineering does a lot more for getting games working and supporting them than does any other store. Most if not all other stores simply sell games and that's it. If you have a problem with a game, other stores will almost universally redirect you to the publisher or developer with a form letter and wash their hands.
If GOG is unable to get something to work, chances are that you wont find a better experience on some other storefront. The only exception is with newer games where the developer updates the game with bugfixes on Steam and does not give GOG the same bugfixes. This does happen and it sucks, but GOG isn't to blame, the publisher is. Don't buy games from game developers like that as they don't respect their customers.