On monday I placed an order w/ blueviking and never got a 'shipped' status. I later realized this is because I marked "Combined Shipping" on accident. I've sent him 2 PM's since then asking simply to cancel my order so I can get my BTC back. Still no response. What action should I take, if any?
It's only been 3 days since your order, correct? If he hasn't changed it by (I believe) four days, you ought to be able to cancel the order yourself. If this isn't an option, you can file a dispute. However three days isn't a terribly long time, so you may want to give it a few more days.
You can also PM him asking if you can get the funds for shipping to him in some manner. I assume the "combined shipping" means that it didn't charge for shipping.