increasing premium without notice

hi my number is ***. i would like to know who gave Cellc to increase my. i signed for a R109 a month premium and saw it gradually increase and now stands at R113.99 its not much but it is an increase and that is a breach of contract and there has been no notification sent to me whatsoever that there will be increases. please resolve and be sure to pay me back every rand that has been deducted unauthorized to date