Air time and data

I bought R15 air time and recharged my MTN sim on +27 (78) *** . I used the air time calling an Mtn number and and when the Id time finished I assumedi was doing to receive the R 170 free or time aNd a certain mount of free data . I try and now call as the airtime is finished and I get a message telling me to put 14 cents in order to get the fee air time and data. I was Nd am still very upset as I had used the full R15 why is it asking me to load more money . This is day light ******* and this is kit the first time that this ha happened where it tells you to load air time of. Ridiculous amount like 14 cents or 40'cents extra. I obtained this extra SIM card in order to call my family and friends who have MTN numbers and this is the service I get! I want my free air time and data otherwise I al going to complain to the consumer protection as this is nonsense !!!!