No help with account

Good day. In October I see they took a double instalment, when I call they tell me that in sept on the 15 th as ussual my debit order went through but it was returned on on the 7 th of Oct this is the reason for double payment. On my side and in my bank it was taken and not retuned. I mail copies of my bank statement on request and because no one come back to me I have my debit order returned this month, the next day it was suspended. I do not get assistance to sort this out. The call centre tell me to sort it out with my bank?