Poor customer service

I have a loan with this company, been paying well by debit order with no hussle. Surprisingly this month of November 2023, they started tracking my account before my salary date which cause charges to my personal bank account. I kept quiet about and let them run the debit order. After the 23rd November 2023 I noted on my transaction history they double debited my bank account. I call them and asked so humbly, I also questioned the debit order that ran before my due date. The guy explained that it is their process to run a debit order during that time as I agreed to the t&c of the contract, fair enough I understood. I then asked about the double debit, the guy responded by saying that he does not see double payments but 1 and he requested I send an email with the statement same was sent on 24 November 2023 to their email address ***. Monday afternoon (27 November 2023), I call making follow up. I was told that they are still busy with investigation, I then asked of the turnaround time. The lady said latest will be Friday (1 December 2023) to get feedback. Mind you I have plans for this money and I decided to contact my bank to ask if the payments were indeed successfully debited, my bank confirmed yes and I then requested for one reversal of that payment. I called yesterday Tuesday (28 November 2023) in the morning as I received an SMS that I'm in arrears. The lady advised me that they are unable to see the email I sent and I had to re-forward the email. She also comfirmed that she sees on the statement I attached that I was double debited however it also shows I am in arrears. I advised the lady that I had reversed one payment and will not be requiring them to resolve my concern. The lady said that she will refer this to the finance department so they can credit the account with that one payment and that will settle everything. Yhoo guess what, was getting calls left and right yesterday telling me about the arrears on the loan. What ****es me off is the last guy, I am not sure whether is Simphiwe/Sphiwe who was so rude and arrogant even when I tried explain the situation to him. He was forcing me to listen to him and agree to what he said. I became rude myself, I told him that he can't just call me and dictate to me without hearing me out first. I hung up. I know my rights as a customer and will not allow any ill treatment from anyone. If I was wrong was going to make means of a payment arrangement but this guy just ruined my day. Your service sucks and you actually do not know how to treat customers fairly.