Deceived by an Investment Company

Unfortunately you should have done your research before you made such a large purchase. It sounds like Goldline puffed their product "well" even though it seems a little revolting on a human level. They can always say that they believe this represents a very good investment in the long term and that in 10 years these coins will net you a profit. It's a matter of opinion as to what a good investment means.

Second, why should Goldline be required to disclose their commissions received?

IMHO you have no case. When you make a deal, unless the other party guarantees a profit you aren't guaranteed that you're getting a "good deal." It's up to you to do your research. As they say, caveat emptor or "let the buyer beware" before making a purchase. Best of luck to you and hopefully you'll see a pot of gold at the end of this investment.