Contract Issue

Approximately 2 years ago, I signed up for a 36 month LTE Home Internet (100GB anytime/100GB Night Owl) contract at R349 p/m. Everything went well, until Vodacom started upping my monthly instalment. As of today, it is at R550 p/m and I understand that Vodacom introduces annual tarrif increases etc. yet an entire R200 extra?

My gripe here is that my allocated GBs stays the same. Vodacom could at least have increased this, thus giving value to the extra I now have to pay. Currently Vodacom is offering a contract with 250GB per month at R250! Thus my question remains, why am I paying more than double that amount, for half of what a new customer is getting?

I look forward to your response.