If repository is down or if you don't know how to use git and demand updates being sent to you as zip files on your email - your demands mean nothing, you are not entitled to be given access to the source code.
You have _permission_ to use it in some license limited way and that's all.
If you _use_ open source code (ie. as part of your product), you may be _required_ to also provide source code, attribution etc.
The developer could exercise their rights and insist on sending you a DVD with the source code on it (and make you pay for materials+shipping) but throwing up difficult burdens is clearly forbidden by the GPL.
Some more extreme licenses grant you, as a user and as a developer, a lot of rights, but also a lot of burdens. I don't think the stricter ideological licenses such as GPL are used much by people who distribute their own code and then decide to make life difficult for their users, though. It's likely that the only cases where this rings true are people relying on GPL code that then want to avoid fulfilling their obligations to their customers.
> you are not entitled to be given access to the source code.
If you're the user of a binary image someone spun from a GNU licensed program, actually you are entitled to that, if it is the Affero license (AGPL), you may be entitled to source code access even if you just use the thing as an online service. Specifically, you're entitled to access to the source code of the modified version that you're actually using.
> If you _use_ open source code (ie. as part of your product), you may be _required_ to also provide source code, attribution etc.
That's redistribution. If you redistribute some kinds of open source code in a product, you may have to provide source code, and that's even if that code is never called. The presence of that code in the image is the key thing, not whether it is used. Use occurs on the target system, by the end user.
If you're an author of a library you have the right to not accept contributions, stop working on it or delete it from github.
The "getting paid" notion is off-topic and has nothing to do with the source being open. If I provide commercial support for someone and implement a solution using open source software, I am the one providing the support and I have no expectation that the original authors will hold my hand.