Increased contract rates

I’m very disappointed in Vodacom. I’ve been on a contract the last twenty four months . My bill has been constant at plus minus R745-R766.15, but suddenly since July it has gone up to R1008.25. I didn’t realize this until I renewed my contracts at Vodacom on Monday September 2nd. I was never told if your contract expires you will no longer get the discounted prices. I am a pensioner and have suddenly had to pay R400 more. I cancelled my contract for my tablet and the lady asked if I would like to renew my contract at a very good price. Why didn’t Vodacom tell me all these things before just putting up the price and not informing me at anytime. I am a loyal customer and expected Vodacom to look after us that have stayed with them for many years. I am going in on Monday and cancelling my two contracts I have with Vodacom. This is not how you treat a loyal customer and get away with it.