Question about my clip in hair extensions?

Ok, so I recently bought some 18" extensions for the very first time. My boyfriend's sister wears them all the time and she offered to sew them for me. She also cut them into pieces and doubled them up so now i've got two pieces with three clips and two pieces with two clips. But because i've got a bob with layers in the back, it's really hard to wear the extensions as they don't cover the layers properly no matter where i put them. Would it be possible to unstitch them and make more pieces by having them singled instead of doubled up? I really want to wear them and up to now they're a waste of money coz i can't wear them!!!