The rear windscreen wiper has never worked.
The driver's seat cable has snapped, so it can't be put forward.
Other than that, the only things to go wrong have been bulbs going and the tires getting worn.
This was my first car, and it has been great. It starts first time every time and causes no problems.
It struggles a bit when you have a car full of people that you try to drive up hills.
The interior is fairly comfortable, but it doesn't leave you with much in the way of elbow room or luggage space.
The speaker system that it came with consisted of a single speaker in the center of the dashboard. Not exactly 'bangin'.
The car is reliable and has taken me ten thousand miles in 6 months without complaining.
When lifting the seats to gain access to the rear, two levers should operate at the base of the seat when you lift the handle.
I had the same problem as you with the driver's seat on my Polo. I noticed that on the passenger seat, the problem had been rectified by lifting the inside lever (the one nearest the handbrake) with a small screwdriver and inserting a screw to hold it open. The outside lever was working correctly and so the seat was still held securely in place and could be lifted when required. I applied the same solution to the driver's seat and the problem was cured at no cost.
I also had a non-working rear wiper. If you remove the panel inside the rear door, remove two or three screws and unclip two wires and remove the wiper arm and retaining nut on the outside they are very easy to replace. I bought one from the scrapyard for £5 and had it fitted and working in about 15 minutes.
Two problems sorted out for a fiver isn't bad - good luck!