You can't call it service that you get from Vodacom

How can I give minus review points, because they don't even deserve 1 star. I am now so sick and tired of Vodacom and their promises.

I have Metrofibre through Vodacom. I have been struggling again with my connection for 7 day. I pay for a 50 mg line and get speeds like 1.23 and 1.63. The modem also disconnect every 10 to 15 min. When I call their *** line, I get told to be patient. I have a 24 month contract, but have had endless problems with this line. Logged more than 20 calls. In the past week only I had to call 4 times I want to get out of my contract and don't want to pay the rest. How do I go about that? I am not bridging the contract, because you take my money by debit order. You are, because I don't get full service and sometimes have to go days without internet.