iv had the same problem with shedding in the same spot on two pieces
and it was down to me, styling a particular area to aggressive,
the hairdresser a one lady salon took one look and seid well its not a faulty piece,
the manufacturer would take one look and say the same thing.
she was however great, actually fantastic she ordered me a new hair system on her.
ill repeat what she seid to me, nothing to do with washing, conditioner ect , just over styling one area,
or maybe your unconsciously scratching that area,
could be a quality control issue but two pieces in the same area kind of rules that out.
you could get 2 weeks without having to rebond,or 3 meaning washing the system less,
I only wash myne twice a month.and that's more to do with a build up of product,

best of luck anthony