The issue applies to any OA Billing installation of 7.0.1 and later version that runs on CentOS 7.0/RHEL 7.0 and later.
Warning: This should be done in a maintanence window, because restart of the Billing service is required.
Prevent the timezone reset by writing it explicitly to
[environment]section, add the following line:
<your_TZ_in_Olson_format>is the timezone you need (for example, Europe/Sofia, or Australia/Sydney, or Europe/Moscow, or the like).
Restart the billing service:
service pba restart