Telkom is taking our money without us knowing it

I have a home fibre contract for R549. I was not informed that the amount can be increased at any time during the contract. Telkom suddenly increases my subscription to R619 . I was never informed about this . Sandenly my fibre as suspended when I contact them they told me I have a outstanding fee of 1200. They have done this before with my mobile WiFi. They need to be stopped