Dropped calls and no signal

I have been using Vodacom as my network for many years however I must say that the couple of months have been hell- half the time I have no signal and my calls get dropped . The office where I am based I have to stand and move to a certain spot every time my phone rings. Upon reporting this I was told that all is well but the problem has just become worse. Even after upgrading my contract to Executive , I am really disappointed and gatvol. Thanks to another service provider that I have had to purchase another phone just to be safe in case of emergency. I live in the Durban metropolitan area so I really don't think I should be suffering like this.