Tired of RCS

Getting a RCS (cotton on ) store-card has to be the biggest mistake i have made this year. I've been paying my account via their self service platform for the past 5 months with no hiccups but last month my payment was somehow nowhere to found on their system.The call agents started calling and harassing me.I tried explaining how my payment wasn't allocated instead she just hung up.Then i was asked to send through my Bank statement,Transaction details ,ID and card number last week Wednesday ,which I all did and was told i'll get a response after 48 hours.8 days later I am asked to send everything again and an agent keeps calling every second day asking for my payment while they failing to allocate my payment.