Users not receive low credit notification

Hello.
Playsms Users not receive low credit notification.
I test it more time.
I use latest version of Playsms.
Here is log :

192.168.1.1 xx.xx.xx.xx 2018-08-02 03:36:51 PID5b623d0a990cd admin L2 sendsms_queue_create # saved queue_code:1af8ce2016e38700feee07d94368b3bb id:684
192.168.1.1 xx.xx.xx.xx 2018-08-02 03:36:51 PID5b623d0a990cd admin L2 sendsms # dst_count:1 sms_count:1 total_charges:1
192.168.1.1 xx.xx.xx.xx 2018-08-02 03:36:51 PID5b623d0a990cd admin L2 sendsms_queue_push # saving queue_code:1af8ce2016e38700feee07d94368b3bb dst:09300000000
192.168.1.1 xx.xx.xx.xx 2018-08-02 03:36:51 PID5b623d0a990cd admin L2 sendsms_queue_push # saved queue_code:1af8ce2016e38700feee07d94368b3bb smslog_id:728
192.168.1.1 xx.xx.xx.xx 2018-08-02 03:36:51 PID5b623d0a990cd admin L2 sendsms # end queue_code:1af8ce2016e38700feee07d94368b3bb queue_count:1 sms_count:1 failed_queue:0 failed_sms:0
- - 2018-08-02 03:37:05 PID5b623d1925140 - L2 sendsmsd # start processing queue_code:1af8ce2016e38700feee07d94368b3bb chunk:0 queue_count:1 sms_count:1 scheduled:2018-08-02 03:36:51 uid:1 gpid:0 sender_id:
- - 2018-08-02 03:37:05 PID5b623d1925140 - L2 sendsmsd # sending queue_code:1af8ce2016e38700feee07d94368b3bb smslog_id:728 to:09300000000 sms_count:1 counter:1
- - 2018-08-02 03:37:05 PID5b623d1925140 - L2 sendsms_process # start
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 simplerate_hook_rate_cansend # allowed user uid:1 sms_to:09300000000 adhoc_credit:10 count:1 rate:1.000 charge:1 adhoc_balance:9
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 sendsms # saving smslog_id:728 u:1 parent_uid:0 g:0 gw:gammu smsc:gsmusb s: d:09300000000 type:text unicode:1 status:0
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 sendsms_process # saved smslog_id:728 id:232
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 gammu_hook_sendsms # saving outfile:[/var/spool/gammu/outbox/OUTA20180802_33706_00_09300000000_728100011100010.txtd] smsc:gsmusb
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 gammu_hook_sendsms # saved outfile:[/var/spool/gammu/outbox/OUTA20180802_33706_00_09300000000_728100011100010.txtd] smsc:gsmusb
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 simplerate_hook_rate_deduct # enter smslog_id:728
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 simplebilling_hook_billing_post # saving smslog_id:728 rate:1.000 count:1 charge:1
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 simplebilling_hook_billing_post # saved smslog_id:728 id:527
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 sendsms_process # end
- - 2018-08-02 03:37:06 PID5b623d1925140 - L2 sendsmsd # result queue_code:1af8ce2016e38700feee07d94368b3bb to:09300000000 flag:1 smslog_id:728
- - 2018-08-02 03:37:07 PID5b623d1925140 - L2 sendsmsd # finish processing queue_code:1af8ce2016e38700feee07d94368b3bb uid:1 sender_id: queue_count:1 sms_count:1
- - 2018-08-02 03:37:40 PID5b623ab612874 - L2 gammu_hook_getsmsstatus # smslog_id:728 unlink the_fn:/var/spool/gammu/sent/OUTA20180802_33706_00_09300000000_728100011100010.txtd p_status:1 smsc:gsmusb
- - 2018-08-02 03:37:41 PID5b623ab612874 - L2 simplebilling__finalize # saving smslog_id:728
- - 2018-08-02 03:37:41 PID5b623ab612874 - L2 simplebilling__finalize # saved smslog_id:728

Sorry, its OK
but how can I change interval checking for this event ?