## get default cust_payby and change it. For old v3 selfservice that upgraded to v4. this is for v4 only
my ($cust_payby) = $cust_main->cust_payby();
## get default cust_payby and change it. For old v3 selfservice that upgraded to v4. this is for v4 only
my ($cust_payby) = $cust_main->cust_payby();