Can you imagine what would happen if everyone who is a member of this site could add spells? Really? Think about it.
Yes, you can join more than one coven. People do, if they have the time and energy to keep their contribution qualitative.
If you don't like how the site is run, you can demonstrate you have something viable to contribute, then maybe at some point, admin. will listen to your views.
Or, you might like to ask for your money back!