Just to give you guys an update on my power steering issues - As I'm getting rid of the car this month I eventually decided to go for the cheapest option, and that was to simply change the fluid. Ford wanted £70 for this job. I can't believe that as it's such an easy job - a four year old could have done it!
Well so far so good. The power steering isn't making a noise anymore and the steering itself is no longer heavy. For the sake of buying two bottles of power steering fluid that cost £8 all-in, I'm very happy.
So, my advice is - If you ever have the same problem, go for the cheapest option first, and if that doesn't work, get the pump changed.
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God gave me feet, and Ford gave me pedals. I intend to put both to good use.