Unhappy client of mondo

I have a contract with telkom through mondo, they promise me 3000 minutes to call telkom line on a monthly basis for 12 months but now they only give me 50 minutes and also the data they are not giving what they have promised, the monthly installment have increased from what we agreed on I have sent them an email but they never rep****. I am not happy with the services if it is possible I would like to deactivate their services because it's not what we agreed on. Thank you