Telkom Reduction in DATA quantity. Unhappy customer

I have been a customer with telkom for over 15 years, i currently have LTE internet with 100Gig day and 100Gig night data on a 2 year contract. My contract has come to its full term and now is on a month to month basis. ONLY to find out that my data reduced to 50 Gig day and 50 Gig night for the same monthly installment. I have tried to contact telkom, logged call, went to their telkom shop but i cannot resolve this. The contract said nothing about reducing the data once full term. Never have someone explained this to me when taking the contract. I was an happy customer, but now i feel exploited and i am unhappy. Telkom you need to fix this!