Rude debt collecting agents

Hi there, My statement state payment is due on the 6th of August 2020, I have had 3 calls in three days and I tell them the same thing, that I will pay before the 6th. They are not equipped to explain or answer my questions. The last person to call me hung up the phone on me. Please assist or refer me to where to someone that can help me. Looking forward to hearing from you. Regards PHILILE MBOKAZI