Co-Payments

I have a co-payment of R500 a month for my chronic medication, two days ago i received a message that my order cant be place as the amount of R1015 is outstanding. In May 2020 R1015 went of my account for Medexpress and June 2020 R500 went of my account, i did forward proof of payment and Medexpress still say they did not receive the payment. I need my medication as with the Covid19 i am most vulnerable of getting sick. Please urgently help. Ref MX00092ZF9 - ID ***