Rear windscreen wiper fault

I recently purchased a Freelander TD4 and I notice that the rear windscreen wiper blade only covers about 30% of the window. Does not even reach the vertical. Thought I would just take the blade off and refit it it slightly further round so it would reacher higher but could not get into it. Do you need to take the mounting of the spare wheel off to get to the blade? Any advice help experience of others most appreciated