Hey interesting to hear your experience with rapture hair extentions. I have been working with them for a year now and find them to be the best system i have seen. I have had mine in for 5 months ( yes! Far too long!) The only time i have seen them slip out was when i coloured them and put them in when the tapes were still a little damp. Or the other thing could be if your client had a build up of synthetic shampoo and cond on the cuticle prior to your application. If there are patches where they hair has come out perhaps you need a slightly thicker section, i always think of the section needs as much hair as the amount of hair on the weft, if the hair is very fine try cutting them in half.
Hope this might be a little helpful and would love to hear some other experiences or tips for rapture extentions..