perming hair from hell

Hi and more expressly HELP!! I need ideas, advice, tricks, secrets, anything and everything that will make perming my mothers hair something besides an extremely frustrating exersize in futility... I'm a cosmetologist and while perming isn't my strong point, I have no trouble with other clients. My mother has especially thick, coarse, grey hair. She insists on wearing it short and CURLY, so I cut her hair very short (buzzed) in the back graduating to about a 3" length on top (no weight line). I set her hair on blue and pink rods with a few yellow around the edge as it gets too short to wrap. I have started having her use "Prell" shampoo about a week before we perm and I lotion wrap with an alkaline perm. She has spots on her head where the perm takes a weak curl EVERY time I perm her. She's getting just under 2 months in "curl wear" with one haircut between perms. Although she wears her hair short, I'm not cutting out the curl, it simply won't hold. Her hair is so strong that when I'm wrapping the yellow and sometimes the blue rods, the hair unwinds and pops right off the rod. I'm using extra large papers with a book wrap and I make sure there's plenty of coverage on the hair section. I've tried sitting her under the dryer, exothermic perms...everything I can think of, however her hair is getting progressivly more stubborn and her perms are lasting a shorter amount of time. WHAT CAN I DO??!!!