If you want to play safe pay by credit (not debit) card and then you're covered by the credit card company if you dont get your goods, (in this case your travel) I think as long as the value of the transaction is more than £100 (check your card issuers small print to make sure)

But I wouldnt worry too much about your money, this is just a bit of predictable sabre rattling by the steam Packet, they've had their monopoly broken so they're threatening to take their ball home.

I'm just pleased the Manx government appear to have stood up to them for the first time in a long time, the job loss blackmail obviously hasnt worked so I wonder what the next stunt will be??