If the consensus is that it's a black sun coral, and it was sold to you as a candy cane, id bring it back for a refund.
That is a significant difference, not only in terms of cost but also, as people have explained, in terms of how you care for it. If it is a sun coral, it is non-photosynthetic. Doesn't make a whole lot of sense why a non-photosynthetic coral would be called a sun coral, but I digress.
This would be like adopting a dog, thinking you understood how to take care of it, but when you get home you learn that the dog is diabetic and has an expensive custom diet that the seller neglected to mention. If you are okay with the extra care associated with feeding a coral, go for it. But nothing wrong with taking it back, especially if it was sold to you as a completely different species...