Welcome to the forum
Service warning required reset using something like Fiat ECU Scan but you need the full working version which is £50 plus all the cables (another £30-40)
the Glow plug light means one has died and probably killed/is killing all the other plug, this is because they are always wired in series and if one goes it takes the others out, a new set is probably about £50 just as a warning your car won't start as the colder mornings set in
The Climate control sounds like it could be an earthing issue although I would have suspected problems with other things like dash lights and switches not working or it could be a loose plug/wire, getting to it requires you to remove half the middle of the dash though. however you can accesses it with diagnostics (as mentioned above to reset the service light) which might give you some idea of whats going on.
I would have thought that if the climate control was completely losing power then it would cause a can-bus fault and your multifunction display between the speedo and the rev counter would start flashing.
what do you have the climate control set to? if its full auto then the computer will turn the fan up and down as required.