Very poor network!!!!

I have a data sim card contract with Vodacom since last year. I have been struggling with poor network connection since early this year. I have reported this issue numerous times but till today, I'm still struggling. each technicians keeps stating that it could be because i am using a dual Sim card phone. if this was the issue then the issue would have existed from day one. I want my contract cancelled so that i can get value for my money because currently, my money is going down the drain. Im sooo frustrated!!!