If your NEW RV has a 30-Amp service, then I assume it is a small travel trailer because most RV's now have a 50-AMp service.
The manufacturer did not do you any favors using a fuse for your input service because it will do just what you are experiencing, blow the fuse.
So, what is happening to you is that you are drawing too much current overall, and you need to learn how to manage your power usage. You see, some of your RV appliances, like your AC can draw a surge current that if you are near your 30-Amp limit, might blow your input fuse.
The good thing is that your dealer did put a BREAKER in the circuit so that it can be reset, rather than you having to replace a fuse.
The bad thing is that you really need to figure out what you are using in your Rv that is using so much current. I have written a Hub that lists the typical current drawn by most common RV appliances, and sometimes, you just have to turn OFF one appliance while you use another high current one.