I've completed several of the free CSC offers, amounting to around 148 CSC, but haven't received the CSC yet. I'm not sure if there's some step I'm missing or a rule I forgot or what, but I'm getting a little peeved. Help please?

Lots of the offers never pay out, even if you provide the proof that you've completed all the steps. It's just the way it is. Just keep doing as many as you can, and hope that some will eventually pay out. It's frustrating, I know. :/

There was a thread about this over in the Problems&Bugs section. The general consensus is that Radium One used to be really iffy with payouts but now it's just completely stopped once Subeta started experiencing the DoS attacks. It's a major bummer because I, like you, have well over 100 csc that I should have earned but it seems that even reporting to RadiumOne does nothing anymore. :/