How long should I expect the auxiliary drivebelt to last on a '93 854?

I ask because my garage has just changed it after only 11K miles / 9
months since the last new one was fitted.

Seems a bit short to me that! Wondering if there's a parts warranty I
can invoke.

On a secondary note, it was put on in an attempt to cure a god-awful
rattling / squealing noise coming from the cambelt / auxiliary
drivebelt area of the engine when cold (ie, first thing in the
morning). Later on in the day, the noise tending to go away (though
not always).

With the new belt fitted, the squealing has gone (for the time being),
but not the rattling when cold.

Can anyone shed any light on this problem? I'm not too concerned about
the noise itself, but more worried that it might be a sign of an
imminent failure of something!