I believe what you are saying is that your analytics is reporting a large number of visitors are using mobile devices, but the experience on those devices is less than optimal.
You don't need a mobile application, you need a better web developer.
A proper website is "responsive/adaptive" to three "snap points". What this means in plain English is that it has a layout for the desktop, the tablet, and a mobile phone.
The only reason to spend money for a mobile application is because you need some feature only an application can support.