It happens all the time. Plus whenever something like this happens it would be evolution reaching out to the casino telling them "Something went wrong here, you need to adjust their balance" - never the other way around.
Fair enough.
I'd go on to say based on your experience that it's not unlikely then for Roobet to have been alerted by evolution for providing them with a wrong bet multiplier.
Why then did Roobet take so long to point the wrong payout(s) to OP?
OP supplied proof that an explanation wasn't immediately provided to him through communication with the casino.
This is what irks me the most. If the casino had the info on the wrong payout they should have provided all the clarity they could to OP.
If there's more to the story the casino are free to post here and clarify.
If OP is lying by omission it should be easy to prove from Roobet's side by providing some screenshots and an explanation.