Kulula.com called numerous times no answer flights changed without my consent given

It is impossible to get hold of Kulula.com. I have called numerous of times the valls just goes unanswered we have made fight bookings for August 2021 to Cape Town we have received an SMS that our flight details have been changed without our consent.

There is a reason why I choose a specific times and dates for my flights. I want my fight details to remain the same as the day that I booked my flights. Where is stated on the terms and conditions that Kulula can change your flight bookings as they wish without any consent from the person that made the payment and booking?