I've only used @booster occasionally but anytime I have used it, I've either had the vote or an automatic refund. The one time I didn't get either, I messaged and inquired and it was refunded within minutes.
you know @kingscrown SteemSpeak is not the only server where you spam your link. I've often wondered with the volume of automatic votes you get why you think you need to spam and set a bad example for those less familiar with the platform?