Vodacom Dropped Calls

[CB40]

I travel extensively around Gauteng and Mpumalanga and have noticed that the amount of dropped calls is shocking to say the least.Contacted Vodacom to assist and was asked to change my settings on the phone..Nokia E90.. so it will pick up 3G & GSM signals.Nokia E90 has only Dual Mode,UMTS or GSM and it makes no differance whatsoever what you set it to.This is extremely frustrating.Where to now??