Some people find it so hard to accept that their children are either a) very hard work behaviour wise or b) special educational needs, that they will attack and blame everything they possibly can. You've done everything by the book and in a very professional way, in my opinion. All you can really do is explain again everything the school is doing to support her, and ask if there is anything they can suggest you do that might help (Putting the ball in their court makes them feel valued, and often they will often have no idea!). Make sure you constantly bring it back to her learning - which is the reason why you are trying to encourage her to do her work. If your KS leader is supportive, it will be positive that you have him/her there with you for the meeting - just make sure you brief her first. If they have further concerns and are not listening to your reasons, tell them to take it to the head.