[Closed] Bike Luggage on Plane (Jet2)

I'm currently booked onto a Jet2 flight to Spain in March. In my haste I just added extra baggage for the cardboard bike box. Now it turns out that you have to ring up after you've made the booking and book the bike box on for an extra £60 and can't transfer my extra baggage towards this. Urg.

So my question is.. Does anyone know if instead of using a cardboard bike box I can use a large suitcase style bike box and get away with it? Has anyone else taken a bike on Jet2 without a cardboard bike box recently?

Cheers