It is possible that you will not receive exactly the hashrate that you purchased (At the end of the order, your average hashrate may be less than the purchased hashrate). This can happen naturally due to the variation in hashrate of miners over a short time period, if there are compatibility issues with stratum hosts or network problems, or if a miner drops off and we can't find a replacement.
In cases where we cannot deliver the purchased hashing power, we will automatically credit your account with BTC for the missing hashing power. For example if you paid 0.1 BTC for 100 Terahashes/sec over 3 hours, and you received on average only 50 Terahashes/sec, we will credit your account with 0.05 BTC. You can see the BTC credit in your profile under "BTC Credits Available" on the top right.
If you notice a drastic problem in receiving your hashrate and want to know what the status of your order is, please get in touch with us at firstname.lastname@example.org.