Unfair contact increase

I received a statement for my wifi rooter, purchased over the phone from a vodacom supplier. As per my previous complaint about a product being sold to a client but with no stock. I received the rooter by the end of March 2015. Vodacom decided to increase their tariffs 1 May 2015 with no written confirmation, only an sms. I received mentioned sms on all my contracts except the rooter, as i thought that the R139 that was agreed upon will be safe. To my surprise vodacom increased that amount also with R10. I think that is very unfair, as i was a client with a new contract that was agreed upon R139 and only had the contract for 1month before it was changed. <br> On 11/06/2015 i contacted Vodacom regarding this and another issue. The lady assisted me with the one problem, but could not with the issue of the increase on the rooter. I contacted again on 17/06/2015 and \Rachel"assisted me but couldn't help. I was given a reference no (S3-88N22-2OLT4). Since then I've had no correspondence from Vodacom what so ever. I need this looked into"