All you have to do is call up the moderator phone number for 573 free credits!
If you don't get the credits within 5 minutes, call again.

First, call 0906 900 9100
Then a lovely lady will guide you through on how to get your credits! She might say it costs money to call, but it doesn't. It only costs if you call 21 times or more(but if you call from another phone, you can call more than 21 times!).
Then, you will be told to put in the code. This is where you put in the moderator code.
The code is 26896859

You can call as many times as you want! If you call over 21 times, it might cost you, but all you have to do is call from another phone. If you call 21 times or less, it's free every time! You can have 1000's of credits for free!

If it doesn't work the first time, feel free to try again, but it usually works every time.

Good luck and have fun on Habbo!