If your quilting looks just as good as theirs, then they have no position from which to argue. Tell them you'll be glad to teach them your method sometime and go on your merry way doing what works best for you. On the other hand, if you're just learning to hand quilt, maybe they're trying to teach you using the way they know best. I've found that if I'm taking any class it's best to try the instructor's methods, even if they don't seem natural to me at the time. Later on I may change the methods, but at least I've made a good faith effort at learning that person's technique, which obviously works for her.