Emirates oursources their visa services to VFS Global (which is why you are not getting any help from them).
To contact VFS Global directly about your application use this form on their website.
Once you arrive at Dubai and descend into the immigration hall - veer to the right and you'll see the immigration officer's counter.
Simply approach them and explain your situation (they are well aware of the glitches in the online system); they will either extend your visa; or invalidate it and issue you a new one with the correct dates.
Since you have applied for a visa from Emirates you can also check with Emirates Holidays (counter is on the left once you descend to the immigration hall); however they most likely will point you to the immigration help desk.
If the visa needs to be re-issued or extended, the entire process takes at a maximum 30 minutes. You can use this time to relax from your flight or grab some refreshments (there is a Dubai Duty Free kiosk at the far end of the hall, opposite the elevators).
As your visa is valid - you can pass through immigration successfully . doDo not do this as overstaying in UAE has hefty fines and you may be barred from applying online (and will have to resort to booking hotels and using their visa services).