3 options...
a) pay a good detailer (not a mere valeter) to full restore you paintwork, this could take upto 2 days of correction and a minimum of £100, and thats cheap!
2) pay a bodyshop to respray, or maybe just a blowover of the whole car to blen in all panels, time, a week or so, with 6 weeks for the paint to cure, cost, at least £200
thirdly) restore it yourself, many products will be needed, methods to be learnt and lots of patience...
first you will need to clean the paintwork, using shampoo will make it look clean, but it still wont be clean, you need to decontaminate the paintwork, good shampoo £10
car pro iron-x is a deironiser will remove , yes you guessed it, iron contamination, also known as industrial fall out £14
autosmart tardis is a tar remover and will remove tar £25
then you need a good clay bar and detailer kit, meguiars is fantastic £25
the paintwork is now clean and ready for paint correction
with a DA preferably, (£200) start with a mild cut compound, do a panel at time, work up the grades, to medium then to harsh, when done, work back down the grades, harsh, medium, mild
then a good filler polish, autoglym super resin polish hasnt really been rivaled, although dodo juice lime prime comes close
then a glaze polish, poorboys blackhole for dark cars, or poorboys white diamond for light cars
then seal it with a good sealant, chemical guys jetseal is brilliant
finish off with a good wax, whatever takes your fancy, soft wax? hard wax? natural or synthetic? color charged? liquid or paste?
hope this helps, just a basic guide