I think credits are very expensive now. 10€=250 cds would be better. Credit's current value is:
10€-158 cred (paysafecard for example)--> 158/10=> 15.8 creds per euro.
If you need 1 000 credits/month, you have to pay:
1 000/15.8 = 63.3 euros
*If you load in CREDITS BONUS week:
X+0.3X=1000; 1.3X=1000; X=1000/1.3; X=769.2
So you have to load X credits=769.2.
769.2/15.8 = 48.7€
Briefly, if you want to be on top5, you need 1 000 cds/month, and you need 48.7-63.3€ to load those credits. That's why people don't play.
If you want to play for top position, you have to spend approximately 50-60€/month.
Who can spend that? Max. 10 players, that's why this game is getting bored, because good players decide not to play.