Rain Internet service provider have inconvenienced me

Rain Internet service provider have inconvenienced me. At the beginning of the month I paid R838 because they said I owe them so I did pay , then they came again and debited my account with R108 I didn't have a problem the next day they refunded me the R108 I was confused but I said maybe it was a mistake on there side. Now I pay on the 1st of every month but today they blocked my services and they say I must pay the R108 when I don't even have money