The windshield washer reservoir is chassis-related, not RV-related. Any normal auto repair facility should be able to handle the project. Just call in advance, letting them know over the phone that you have a motorhome, not a van. This would likely require that the repair needs to be done outside. They should be able to quote a price without even seeing the motorhome.
Doing a quick search, it appears access to the reservoir is done by removing the tire, then fender liner. If that is true, it should not be a challenge for a mechanic or DIY'er.
If you had water in the reservoir that froze, that may have cracked the reservoir, but if not, then you have a chance the leak can be repaired. Maybe the pump itself is leaking, or a gasket or hose. Given that you live near Orlando, FL (per your ID) freezing is an unlikely scenario, hence something else is likely leaking, not the reservoir itself.
