Vodacom - BAD BAD Service and contract increase as they wish.

I opened a Vodacom contract in 1997. Since then I got the Cell number. No in 2018 after lots of renewal and ...contract they increase my monthly instalment with R50. without any notification. After I phoned the call centre for 5x. Some said to me that I signed the contract and it stats that VODACOM can increase the instalment as they wish. I know R50 is not a lot BUT Why? No notification from Vodacom Agents does not know what they do! Can not see Straight away what's the reason for this increase.

I will definitely not renew my contract again if this is the kind of service a loyal person receive from Vodacom.

Thank your but no Thank you.