14 or 16" hair extensions

Can anyone tell me where i can order 14 or 16" pre-tip hair extensions? i was using Kristen's d-lUX but the shortest i can get is 18" and the girl i did them on says she was shedding alot and the extensions were coming out in her brush. She has had them in for 4 months and now wants them out and asked me if i could order a shorter lenght instead of cutting the 18" down. My mind is blank right now so could someone give me a few names of companies that have that lenght  that are pre-tipped. I know jet extensions but everyone seems to be giving it the thumbs down.  Thanks much!!!!!!!

    You all are "simply the best"

                                             hairgirl1