Iberia Express – upgrading cash ticket to business

[SteveR]

I have bought 2 tickets Optimal Man – Mad next March (Peak) Cost £180 for the two of us. (not sure if that is relevant)

I can see seats available on other peak dates (Jan 2) just not our date at the moment

If seats become available how do I / Can I upgrade? But more importantly, how do I work out the cost

TIA

[SteveR]

Also, can anyone recommend a reasonable hotel in Madrid (no points of any type) for one night We are connecting to our MaD _ Mia flight next day