Hi
To answer your question I have only this week had the same problem. I took the oven out of the housing to check the connections and earth and could not work it out myself. I went down to our management company AEA in the port and they gave me the name of the electricians they use on our community. They have had the same problem many times over. I gave them a call and they popped out the same day. They had to unplug the oven and change the wires over in the plug. They then ran the oven for 45 mins to dry out the moisture as this is also a problem if unused for such long periods and can also trip the electric.
Altogether it took an hour and they charged me £25 Euros. Very helpful and very good value. Better than in the UK. All worked fine for the remainder of our time out there. Their number was a spanish number of 952892398.
Hope this helps. Good Luck
Mick