Using changelly certainly was a one time mistake for me.
I'm letting you know, because I whish somebody would've told me before...
I know this thread is a little old, but usually they operate smoothly--and I'm basing that simply from my dozen or so transactions with them--however, they can and do
mess things up from time to time. Fortunately their customer service isn't as bad as, say, Yobit's but there's definitely some room for improvement as far as I'm concerned.
Changelly are another place that springs KYC on you out of nowhere and have openly stated they will keep your money if they decided you haven't 'passed'.
Did they start requiring KYC? I haven't used them in quite some time and won't be henceforth if they do require it.