You should bring a witness to where you are supposed to pick up your child. Document every missed time. Then, file a motion to show cause.
You also need to send her a letter via certified mail
I was at _____ at hour______ for the court ordered visitation of our child(ren), ______.
You failed to produce our child(ren). I would like to schedule an alternate time to make
up the missed visitation. How does ______ sound? Please let me know if this works
for you, otherwise we can work out an alternate time.
I will be at _____ at ______ time for my regularly scheduled visit with our child. Please
be there with them.
cc: Court File, your lawyer, etc.
Make sure a letter gets to your file. Send a letter like this EVERY time she misses the visitation. Then after about three times, file your order to show cause, and ask for make up time with your child. With this kind of documentation, the courts should grant you your time. And if she keeps it up, then they will get her for contempt of court.