Tencent-backed travel agency Tongcheng-Elong must fix problems with its personal information collection policy, because it doesn’t fully inform users of how their data will be used, China’s Ministry of Industry and Information Technology warned Tuesday.

The ministry met with company representatives after investigating complaints from the public about the train-ticket service offered by Tongcheng’s WeChat mini-app. Tongcheng has not fulfilled part of its service agreement in the mini-app, the ministry said, without giving specific details.

Tongcheng, which counts internet giant Tencent and travel app Ctrip among its investors, made its debut on the Hong Kong stock exchange on Nov. 26 and is one of the country’s largest booking platforms.