Discount Supplements internet-based company Internet

I placed an order with Discountsupplements.co.uk over 1 month ago.  I received a confirmation e-mail stating my order had been received and my card was charged 1 day later.  One week after placing the order I received an e-mail that one of the items I ordered would not be available for 2 weeks so they would provide me with a coupon to use on my next order.  I immediately called them and said that would not be acceptable - they needed to refund that portion of the order. 

They confirmed during that conversation that the order was still being "processed" in the warehouse.  I asked to cancel the whole order as it was taking too long - they refused saying that you can not cancel an order after placing it.  I looked on their website and anything in writing that I say stated 100% satisfaction guaranteed, "easy returns", etc....  it turns out that if you return something you need to dowload a form from their website fill it out and ship it to a different address and then they will only refund you 90% of the original purchase price - they charge a fee for returns! 

I have had multiple phone calls and e-mails all giving different reasons for the delay in shipment, but it has been over a month and I still have not received the products that I have already paid for.  My next step is contacting my credit card company.