Stay away from Vodacom contracts

I took a 300gb Sim data with vodacom for R299 per month. The first month they debited the right amount. The second month the debited R461, I called them and the guy by the name Christopher told me there are subscriptions that are added and I didn't know of as I didn't add anything on my contract. He told me he removed everything and that on the next month I'll pay only the 299. To my surprise this month they are charging me R512. It look like vodacom is doing this to rip people off. Now they are saying they'll cancel it, why didn't they cancel the first time I called. It looks like it's their way of robbing innocent people. Now if I want to cancel they are saying I must pay penalties for canceling a contract early whilst they are not sticking to our contract. This people are ********