A：谢谢您长期支持我们的业务。

xièxiè nín chángqī zhīchí wǒmen de yèwù 。

Thank you for your long-term support for our business.

B：您太客气了，我们是互惠互利。

Nín tài kèqì le ， women shì hùhuìhùlì 。

Don’t mention it. We're mutually beneficial.

B：为了答谢您的信任，我们决定升级您的会员等级。

wéile dáxiè nínde xìnrén, wǒmen juédìng shēngjí nínde huìyuán děngjí

In return for your trust, we have decided to upgrade your membership.

A：非常感谢。

fēicháng gǎnxiè

Thank you very much