Please correct me if I'm wrong?

I have an Xbox 360 and a TV that I'm not currently using. I told my girlfriend that her 7 year old daughter can have it for Christmas and we both agreed that she can have it on the condition that she behaves ( Santa doesn't give presents to kids on the naughty list). Lately her behaviour is appalling. So I told my girlfriend that she's no longer having the Xbox and TV due to her behaviour. This resulted in a massive argument and I'm being made out to be the bad guy for Christmas. Let's not forget the fact that her daughter has already got an iPad, new bike, new scooter and literally a room full of toys. My argument is that she is rewarding her daughter with bad behaviour and now she's off to the shops to get an Xbox and TV regardless. So am I wrong for caring about her daughter's future? We have a daughter of our own on the way and I feel that the big sister now would be a terrible example to follow for our little one if this continues. So am I wrong?

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