MWEB has no after sales customer service

So 3 months ago I changed my banking details. I went tot he Mweb portal and chugged my banking details there for the debit order as well. FOIr 3 mo the now, they haven't changed it and keep debiting the old account and it bounces and they send me some mail I haven paid. I even emailed them but no repose at all. Their customer service totally sucks.