Used cars can be a nightmare. You often take a risk when buying one not knowing if there is anything wrong with it or if there is anything likely to go wrong soon. Too many people get tricked in to buying a car that the previous owner knows is on its last legs or is going to cost a lot to get it through its next MOT and this can be awful for the new owner.
If you have a car that needs repairing always try and find out the full extent of the work required before they start, it may be that you even have to pay a labour charge for them to spend and hour or so stripping it down to find out what the issues is but this can be well worth the money. You may find that actually the car is going to cost far more to repair than it is worth and therefore you are better to scrap it and start again. But on the other hand sometimes it is better the devil you know and you may want to pay to have the issues fixed knowing you have peace of mind that it has been done and should not go wrong again in the near future.