customer service
US /ˈkʌs.tə.mər ˌsɜːr.vɪs/
UK /ˈkʌs.tə.mər ˌsɜːr.vɪs/

1.
the assistance and advice provided by a company to those people who buy or use its products or services
:
•
Good customer service is essential for retaining clients.
•
I had to call customer service to resolve the issue with my order.