These cars are very susceptible to battery condition. If the steering failed, becoming heavy, battery is more likely suspect than steering motor.
As said above, the torque sensor is the bit that fails mostly, requiring the top part of the column to be swapped. Just done mine on the Panda, with one from these guys,
https://www.fiatforum.com/western-power-steering/ (£180 - lifetime warranty)
Give them a call, very helpful.
Changing it is not that difficult if you can wield the spanners yourself.
If it is not the battery, you could try asking the dealer. One day out of warranty, they might offer something. The worst they can do is say no.