She does

"Well, it couldn't hurt to try it on then" Ginny says, turning around and lifting up her hair, exposing her neck to Harry. He slips the collar around her neck, fastening it in place.

Instantly Ginny feels the change, the sudden urge to submit to Harry. She drops to her knees, her hands laying on her thighs, palms up. Her head is bowed down in submission. She tries to fight, just to see I'd she can stand but the magic is strong, keeping her in place.

Harry was rendered speechless as his strong red headed girlfriend was now the picture of submission. Harry wondered to himself