Unprofessional Conduct

I received a call from an extremely rude collections representative. I had initially contacted the agency for an arrangement to pay off my outstanding MTN account balance of R 400-24 which is currently sitting with VVM Collections. A certain Revoningho Makamu instead of speaking to me as any other agent/representative would contact me and remind me about honouring the arrangement made she raised her voice at me, when I attempted to deescalate the situation she continued with the rude behaviour until such a point that I put the phone aside and proceeded with my work. I am extremely unhappy regarding this call as I was at work at a very busy pay period and to have to deal with someone that is disrespectful, cannot communicate and does not have any telephone ettiquecy is extremely unacceptable. She has no level of EQ and I informed the collections agency that I will be cancelling all my subscriptions under MTN as I have been treated with utter disrespect, I was not contacted when the account was also handed over and this impacted heavily on my credit rating.