I'm sorry you're having problems. Not all pre-cuts are created equal. I have heard stories such as yours from many who have purchased inexpensive pre-cuts. Best advice for the future is to stay away from them and only purchase high quality pre-cuts such as Moda.
To help you salvage what you have now you may have to give up using them in strips and cut them into smaller pieces. Another suggestion is to make a strip block where you can use different width strips. These are often sewn on a stabilizer and then cut to size. Google strip quilts and look at some of the pictures to get some ideas. You'll still be able to use your fabric but probably not in the way you intended.