An alternative to Messenger for user support

Hi hackers,

I am looking for alternative to facebook messenger to handle user support. This is for the mobile app cashcoach.io

Requirements:

• NO javascript integration
• chat support similar to facebook messenger: hosted on a static address like: m.me/CashCoachAI
• cheap: max $10/month
• allows to assign tickets to team members

I tried all the classic user support solutions, and they all require to integrate some javascript snippet. I want a solution that will open a support chat in a web page.

Does anyone know any solution?

Thanks