I'd contact the person/place you purchased the quilt from. It sounds like they set the lines, and if so, they won't ever come out. Sorry....perhaps a refund is in order, if possible. So sad.
I've read about this same issue a million times on the longarming site, and folks have tried just about everything in the book - all to no avail. If the lines are set, they are really set and never completely come out. I'm sorry this happened to you. :(