Viscous cooling fan loose

Hi, I was told after my car ('98 Maverick 2.4gls) passed its m.o.t there were a few 'advisories'. One of which was my viscous cooling fan was loose. The suggestion was I needed a new one. Supplied and fitted I was told around £400! (that was getting the part from Ford dealer and fitted at local garage where I had m.o.t)
Firstly.. Can the fan coupling be tightened up?
Secondly.. if it cannot be tightened and needs replacing, would a fan off a '93 2.7td Terrano 2 fit?
Any help would be appreciated as the garage did usual thing putting fear in me that it will cause fan blade to cut into my radiator if i dont get it sorted!
Many thanks!