Vodacom and data coverage of 3g a lie

I have a modem and tablet ,cellphone sim form Vodacom the coverage is so poor is remain on edge I did complain numerous times the technical guy said they don't come out after five this is a nightmare but prices go up and data very expensive .Everyone that want to buy a tablet you coverage for the first month so fast its a lie after that its edge Vodacom really treat its customers poorly They have the nerve to send sms I experience high level of broadband the CEO probably find that effective