Bad attitude of RCS debtcollection agent

I do have an Poetry account with a credit limit of R13000 with them.I paid every single month on time, even during Covid 19 The last payment was just over R500 oustanding which I paid on Saturday morning 22 August 2020 to clear my account in full! An agent from RCS debt collection called me today 25 August 2020 and spoke in a rude way to me , after I told him I have paid already on Saturday , the outstanding amount he told me to send an email with proof of payment, in a nasty way. I feel like closing my account, after his telephone call, and never use this account again! What a bad reflection on your company., to loose a very good customer with a good credit record!!!