Jet Account ****

My mom is 63 years old, having an account with Jet stores. Everytime she pays the balance increases. She has been to Jet stores several times to get the clarity. They are also charging her for the airtime she canceled and they confirmed it is canceled. Last time she went there they said she should call herself and it is costly. When I try to call they say they can't help me because I'm not the account holder. She has been at Bethlehem Jet stores several times. Her ID no. ***. Her name is Matsheliso Christine Mkhosana with contact ***. Please assist she is pensioner and she is stressing.