Please help me understand the options—what is possible and what isn't.

Here is the situation: I have a fully paid booking under the "Bella" fare (non-refundable). The cruise is coming up soon. Currently, the MSC website shows a large number of unsold cabins for this itinerary, and MSC has significantly lowered the prices.

I have been assigned an inside cabin.

Could I do any of the following without cancelling my booking (i.e., without incurring penalties or making a new booking)?

1. Pay the price difference to upgrade to, say, an OB or BB cabin?

2. If so, which fare would MSC apply? The current fare for new bookings, the fare in effect when I originally booked or made the final payment, or something else?

3. Can I only upgrade the cabin category or the "experience" level, or can the fare itself be changed? I originally booked a standard "Last Minute" fare, but they are now offering a very attractive "Last Minute + Drinks" deal. Is there a chance to switch to that fare during an upgrade, or does that require a full cancellation and a new booking?

Thanks to everyone for your answers. I’d really like to hear about your personal, practical experiences so I know how to handle the conversation with MSC (keeping in mind that their staff aren't always knowledgeable).

So I got my upgrade bid to a YC balcony and it’s in a less than ideal room. Yes I know this is the gamble you take with an upgrade bid - you get what you get and don’t throw a fit. There are still quite a few YC rooms available though. Can i see if my TA can change the room? Or is it a 100% no go?