Telkom harassed me to the last degree

afternoon having un ending contract with Telkom I made arrangements with them to pay them outstanding R 900 on monthly basis and to my surprise i owe them 370 of which I am the process of paying them,and they handed me to their debit collection this number 011 100 *** call me day and night they even harassed me to the last degree I just want to know from Telkom if this the way to deal with consumers or they don't have any other proffesional way on how to deal with customers,am very disappointed after they dragged my 24 months contract to 29 months and still act in this manner, who proctect us from this behaviour????