There is two numbers that you can use, both of them work but both give you a different amount of credits.
For sixty credits ring 09069 009 100 or for twenty credits ring 0905 657 5575
When asked to enter a code, type in 262 429 56 which is the special habbo glitch code.
This special code gives you a little extra than the average amount of a credits.
A little change, a bit difference ;) !
You're missing out if you're not doing it... What have you got to lose :)