A year later after settling my account with Edgars they tell me I owe them money!

Last year on the 4th of November I settled my edgars account and closed it! The lady at the store gave me the e-mail address and to sent the proof of payment to, as she couldn't put the amount of R17318.54 through the system, but I paid my account electronically anyway. So I sent the proof of account the same day to them! Today an unknown number *** contacts me with the words, that my edgars account is in arrears with an amount of R434.93! Otherwise action will be taken from edgars side! A year later! So Edgars I will definitely not pay anything including this amount, as I do not owe you a cent! Whoever sent me this whatsapp, please take the time to follow up with them!