Edgars demanding money from a closed account

My mother (who is a pensioner) paid and closed off her Edgars account at the end of February this year . Mind you they gave her the settlement amount. She visited the Vincent branch again on the 15th of march because she received an sms asking her for an outstanding payment and they confirmed it was closed. They confirmed that the Travel Indu Policy & Family Provident Plan Policy was cancelled on 16 March 2021. She has visited the branch again to ensure the account is closed. She has called and written emails to the accounts department (as instructed) but they are still sending her smses. ***.