Ford Fiesta drive belt jumping pulley's (fan belt)

Hi All,
This has took 5 drive belts (Fan belt) to figure out it was the smallest that was needed. Having fitted it, the belt now decides to jump off the pulley's.The vehicle i'm talking about is a Ford Fiesta 1.8 Turbo Diesel, it is a 2000 model, with a Endura DI engine, it has 7 pulley's, Tensioner is at the top of the engine, then water pump, then another pulley, then Alternator, then Power Steering pulley, then Crankshaft Pulley,then another Pulley, then back to top tensioner pulley. I would appreciate it if some one could give me a pulley diagram, or point me in the right direction as to fitting this belt the right way round. Pulley configureaction is O top Tensioner,O water pump, under or over not sure, O pulley, O Alternator, O Power Steering, O Crankshaft, O pulley, then back to Top Tensioner.This car has shred 3 belts in less than 12 months, last time missus was out in it, had to be put on a flat back dropped at house, she was not impressed.
Many Thanks in Advance.
Phil Pop.