Ampath Claimed with a wrong medical Aid number

I having a problem here, Ampath claimed for my blood results at Gems in January 2015 with the wrong medical aid number which I never filled in the forms when the sister was taking blood samples and Gems is refusing to pay them and they want me to pay them R1333.70. Gems called them they must write off the Debt because its their fault but they refuse they want money from me.