It's because your country and nothing else.
BWIN has recently imposed limites based on player's country origin.
Especially users from Eastern Europe have faced these limits.
Yes, I know what you want ro reiterate that now BWIN/GB/PB has 10 EUR limit instead of the "old one" of 50 EUR , well this is how they fight against bonus hunters, by imposing such low limits. Very Sadly but ... this is the TRUE !
Life goes ON ! Be happy.