doubtful product !!! 3

Then I changed my cartridges once a year (I do not print many) cartridges delivered during the last 2 or 3 orders barely have lasted more than a month! I am furious given the price paid I just change the "cyan" I notice I installed the 03/03 mark the date on it and the "magenta" installed the 07/03 is reported almost empty.
I wonder if the delivered products are genuine brand "brother" I have a big doubt and fear a product tampering
I expect an answer
thank you