Data billing issues

Since the middle of December 2015 my data started \disappearing". I called 111 and was told that it must be a data setting on my phone. I told the operator that I was an awful long time on the phone not to get an answer. On your operator's advice I then went to the iStore in Cresta twice and they could not find any fault with my phone. Nobody but me had access to my phone and I did not make any changes.<br> <br> On Wednesday called again after seeing my bill online"