Dropped calls and No signal

Hi, I am having a bad experience with Vodacom, everyone who tries to call me at work cannot get through to me. When people call it goes straight to voice mail. Sometimes a call comes through and after 5 seconds it drops. My number is ********** 636 and my work address is 108 Albertyn Avenue Sandton, I have no experienced this when my number was on the MTN network, please advise as this is frustrating and clients cannot get hold of me. Please try to e-mail me to give feedback, because you know, you won't get through on my cellphone due to weak signal.