Incorrect billing and horrible customer service

Vodacom contracts department has a horrible service. They have been overcharging me post my contract upgrade which I did in October/November last year during their black Friday and cyber Monday specials. The deal for my upgrade which I confirmed online and further with a sales consultant who called post placing my order online was for R559 but I have been getting invoiced almost double that amount. When I called to enquire on this I get taken from pillar to post by their consultants and all their stories are inconsistent, others tells me I'm being charged for insurance which I never signed up for with my upgrade and on my invoices it shows theft cover 0-rated and not being charged for, others tell me there's added services which were added to my new contract upon the upgrade but none of them can explain what those added services are and why I'm charged for them as I didn't agree to that, and then others tell me about a video streaming (dstv) I'm being charged for but I don't even have an active dstv account, I only have a showman account which I pay for through airtime top up on my Vodacom number and paying through that. I've asked for the contract to be canceled but they giving me the runaround however they can't correct my account. My invoices are now coming totaled with charges of R700+ and no longer the double amounts they used to invoice and again when I call to get assistance I get given the run around. I'm really exhausted of battling with Vodacom, I've gotten to a point where I no longer want to call them however I'm not happy with what I'm being charged. I've been a loyal customer to them for the past 4 - 6 years, on contract and paying on time with no defaults whatever but they fail to show the same loyalty to their customers. Please do not open a cellphone contract with Vodacom, their services are horrible to say the least.