Groom's mother wants to help pick out wedding dress. My daughter & I don't want her there. What to do?

My daughter is the bride to be and her FMIL, who has no daughters, has not been easy to deal with. She is not supportive of the relationship between my daughter and her son, but despite this, is now trying to horn her way into going bridal dress shopping with my daughter and I, (incidentally, my husband I are paying for the whole wedding) when my daughter has told her and her son has told her that bridal dress shopping is strictly mother-daughter only-including the fittings-and that she will not be asked to come. The FMIL has called several bridal boutiques in the area, asking if my daughter and I have set up appointments and has bombarded my daughter at work with phone calls begging to go, has called my mother's house-my mother has recently had a heart attack-at all hours asking if she knew when my daughter and I were going and has called me at 6am about it. I told her that it was made clear to her by her son and my daughter that the dress shopping was not something she would not be included in and I told her to not ever call my mother again, who is under strict doctor's orders to avoid stress or to call me again. Now the FMIL is upset and is ranting to her family that my daughter is a bridezilla. What do we do when the woman won't listen?