Unprofessional and rude callers

I had a call for the first time from one of your collection's agents - she introduced herself at the beginning of the call. During the call, she was disturbingly rude and did not take kindly to me, questioning the facts she used during our discussions. I asked for her name during the discussion, and she refused to give me her name, saying she gave me her details at the beginning of the call. She ended up dropping the call before we finished the discussion.

Your team was telling me that I owe Rain R1 000 from 2021 - I was clarifying that I cancelled my account years ago and never received an invoice or statement from Rain. However, your caller insisted that I should have received proof of cancellation. When I asked why Rain waited over 3 years to ask me for proof of cancellation - she was very rude.

Today, I received a call from another individual - a gentleman this time. Of course, I refused to confirm my date of birth as I asked him to provide me with the details of the caller from yesterday - he refused to provide me with the details.

Now, I would like to lodge a formal complaint about the conduct of your callers and the seemingly incorrect procedure of branding customers who do not agree with the facts presented to them as rude and uncooperative.

I would like you to listen to the recording with both callers - yesterday and today and advise me of the steps I will need to follow to lodge a formal complaint.