Billing End Date

Hello ,I hope you are doing well. We are using the latest Firmware (Splynx 5.0.6670).If i

have 20 clients will expired today and i want to add 24hrs , 48hrs or One Month

for all in one process ,is it possible?

I am not Using Billing feature,i am add date on Service feature “Billing End date”

and i want to Use billing to add days can tell me how i can do it .

Thanks