Harassment for money from edgars and rcs

Good day. I have always paid my edgars account on time. My last payment was due and i made an eft. Edgars and rcs started to contact me every day demanding payment. I have even emailed through proof of payment, which was acknowledged. RCS continued to call me demanding me to make paymemt. My credit rating has now been negativity affected! And im in the process of getting a home loan. Edgars keeps telling me its not their problem. And RCS does not amswer their phones