Telkom Contract brake after 20 months

Just want to share the following. Telkom have this thing that near to the end of your data contract they change the monthly premium to a higher amount. If you query this, they will only come back after several emails and say it is tariff increase. How on earth can there be a tariff increase on a 24-month signed contract. This is contract brake, isn't it? The irony of it is that the increased amount is the same as my previous contract with them. How can they increase the premium of a signed contract after 20 months, 4 months to go. You sign a contract that for 24 months you will pay each month the amount stated in the contract. Now the change it - contract brake, thats what I call it.