Micra 160SR Fan Belt Squealing

I have a 160SR and have the dreaded fan belt squeal. How difficult is it to adjust or replace as it is driving my missus mad. And therefore driving me mad. Any help would be appreciated.
I also have a 160SR and the fan belt is also squealing on my car. I use a silicone spay... then its quiet for about 15 days or so.

I have heard from a Nissan mechanic, that many of the K12's came with a bad fan belt when new... some kind af manufacturing fault. He said that he has changed alot of these belts.

I dont know how hard it is to change, but I looking to get mine changed soon.
I have a Micra K12 1.2se and I have had a squealing belt problem for ages. I have changed the idler pulley and am now on the 4th belt - genuine Nissan as well as non gen. It is OK for a few weeks then it starts again; retightening dos not work. I considered changing the crank pulley but our local Dealer in Cambridge says they have never sold one so that seems a non starter. Tried belt spray. Anybody got any ideas. Peter