We had the same problem with our son. I tried everything - different bottles, expressed milk, different formulas, different temperatures, different people offering the bottle! I got so frustrated, I gave up trying for a while. I didn't think he'd ever take a bottle - but suddenly, after a bit of a break, he began taking formula from the MAM self sterilising bottles. Now he's 8 months old and he happily takes all his milk from the MAM bottles - what a relief! I've heard good things about the nuk latext teat from others with a similar issue. So keep trying, but if you or she are getting stressed about it, take a break for a while and then try again. Good luck!