How to complain about medical treatment? Any ideas welcome

My elderly neighbour underwent heart surgery in 2011 and was prescribed incorrect tablets by his local doctor ( who was actually substituting for the usual doctor ) Unfortunately these tablets have precipitated a second operation and he would like to register his disapproval of the fact that the local doctor did not liase with the hospital via computer records to ensure correct medication. Can anyone help please?

Sorry to hear about that.

Have a read of this article in Spanish which may give you some idea of what action to take.  You may need to run it through Google translate if you can't read Spanish.

About 15 years ago I made an official complaint to Social Security Head Office about a doctor..   

I will not go into details other than to say  that it was when I discovered I had cancer that I made the complaint.

The doctor in his defence said he had referred me to specialist but that he had not made a note of who it was and he could not remember. In fact he had not kept any records of my visits.  I was a lie but accepted by the Social Security as I could not prove that he had not referred me.

It was a waste of my time.

In this case, you might try asking for the complaints forms, complete them and see what happens.