Thanks for the reply, I called the helpline and was issued with a new sim. A call was also raised with EE. However the issue remains only when I am at work, my desk seems to be in a blackout spot. There also seems to be repair men at the mast which is close to my workplace grounds. There are no issues with service when I am at home or elsewhere, only at my desk. I shall monitor this and call again if it continues. Thanks again.