Balance notifications

[NCbeasty]

Can I set up notifications to customers when:
- their balance is going to 0;
- their balance = 0;
- they are reaching a credit limit;
- they have reached a credit limit

[ksenya]

By default, a billing system sends renewal notifications (provided that an auto-renewal option is disabled) 5 4 3 2 1 0 days before the expiration date.
If an auto-renewal option is enabled, a low balance notification will be sent
10 5 4 3 2 1 0 days before a service will expire.

Add the following parameters to the BILLmanager configuration files:

LowMoneyExpirePeriod
LowMoneyNoticePeriod

> - they are reaching a credit limit;
> - they have reached a credit limit

Unfortunately, BLLmanager doesn' send such notifications