Poor performance

Hi My wife has been using the Libre 2 diabetics sensor for some time now and when it works proberly it is fantastic. HOWEVER...as of the past few months the app**** sensors have consistently failed even though we have gone to great pains to be sure we are applying them according to instructions. Her diabettic doctor actually fitted one and they have all fasiled in one form or another. The return policy works well and they have replaced each one that has failed. Some fitted are quite inaccurate (by some margin) when compared to the traditional blood meter. I have written multiple emails to Abbotts without so much as a reply. At R1000.00 + a pop (not on medical aid) I believe they product should be more reliable.