First, the internet access on a ship can be dodgy at times. It's satellite based and effected by position, weather, capacity during peak hours, etc. etc. But I would say #3 is your biggest hurdle. I think we've all had internet issues while on board ships, and completely understand the frustration especially when trying to schedule things like Zoom meetings. But if you stay quiet the entire week and then talk to them after and say "I used the product for an entire week without a single complaint, but now that I'm back home I want a refund because it didn't work", it's going to sound more like a story than an issue. If you went down to the internet concierge while it wasn't working, they could issue you credits right on the spot. They'd also be able to escalate your complaint right from the ship which essentially gives you proof of your issues for when you do request that full refund later.
Think of ordering a peperoni pizza and when you get home it's just cheese. You decide to eat it anyways and go back to the pizza place the next day and say "the pizza I ordered yesterday was supposed to be peperoni but it's just cheese. I didn't complain, and I still ate the pizza, but now I want you to make me another one for free". I doubt you get a new pizza.