Voltbike mariner front derailleur

[Reema Ylla]

I've been browsing for a derailleur since the chain keeps coming off, I've notice the clamp of front derailleurs might not fit on my bike. Any recommendations?

 

[zap016VOLTAGE]

I own an 2016 Mariner stripper (no fenders, luggage rack, tail light and bench seats)!
Not once has its chain popped off.
The reason may be that older Mariner's chainring had two plastic chain guides.
Newer Mariners appear to have just one.
Having the second chainring guide may fix the issue you're having.
Perhaps you can contact @Voltbike about this.
Good luck.