There may or may not be an additional change agent that we haven't discovered yet, but you're wrong when you say that "Darwin got it wrong": -- the evidence for natural selection and mutation being responsible for, if not all, then a vast amount of change within species or leading to new species, is overwhelming.
There is overwhelming evidcne that genetic change, or mutation if you will, accompanies change, but that's a small part of the story. We've only just mapped the human genome. We know little how it works. We know little what other biological structures or mechanisms may interact with the genome or what roles they may play in its change or mutation.
As for "overwhelming evidence" for natural selection, I'm unclear what you mean. Darwin theorized that random mutation would create many different versions of an organism who would compete against each other for resources until all but the best adapted to the environment have died out. Well there's just no evidence for that. If by "natural selection" you mean that life on Earth seems to have to ability to change to better adapt to its environment, well then yes, there is a great deal of evidence for that.