CSRs are abused by call center managers far more often than they are by the people on the other end of the phone line. The endless push for "better" metrics, the terrible pay, the dehumanizing scripts, bad (or zero) training, optimizing to make every employee interchangeable and expendable, unforgiving attendance policies, treating workers like children, etc. Call centers are brutal environments and the reason churn is often so high has very little to do with abuse from the people calling for help. In fact, the last two call centers I had any insight into (to their credit) had strict policies about not taking abuse from customers and would flag abusive customer's accounts.