UPDATE:
Hashflare has now given me credit for my payment. So in my case, they turned out to be very slow, but trustable.
After a full 10 days of wondering.. I received my first ever email communication from someone at Hashflare, apologizing for the delay, and saying that they've accepted my payment for hashrate:
Sorry for the long time it took to respond to your message.
Your purchase ID: 4843891 was not confirmed as it is only partially paid: we received 0.0591 BTC out of 0.0611 BTC total.
We have confirmed your purchase manually and added 4.74 TH/s SHA-256 accordingly.
Please don't forget about your wallet's commission in the future (we recommend checking the exact commission with your wallet provider).
Okay, yes, that apparently did happen. Now that I look at the blockchain transaction, that's something I hadn't noticed, that the amount transferred went lower, without my being notified nor warned about it by the exchange I transferred it from. So, don't do that! But, hanging for ten days wondering if they were deliberately not answering looks very bad. But now it's fixed, so they may need a lot more extra time right now than even patient customers would expect! I have just removed my negative feedback on Hashflare's profile here, and updated it with positive feedback.
https://bitcointalk.org/index.php?action=profile;u=514754Everyone: please update us with what happened with your payments!
i sent the ticket around 7 day ago .. meaning i need to wait 3 day more.