Usually its about an year. Look for 12M written in open box icon. It means 12 months from first opening the box. Many car polish carries expiry in this icons. 12M, 24M, 36M because it gets expired when it contact with air and get oxidized.
You need real pro electrician now to remove the CD changer out and then open it and get the CD and pin out and see why at first place CD got stuck any plastic rotor on side is broken or jammed.
Your mechanic is qite right, but if it continue to comes after few days then show again to mechanic and ask him to check if engine oil isnt leaking and getting burnt near manifold area.
Also check f brake oil isnt getting leak and dropping on manifold area, as that is more dangerous as brake oil is highly inflamable and also catch fire if it drops on very hot manifold.
If you also see excessive smoke behind exhaust then that means piston rings are leaking the oil in engine fire area and getting burnt. You need to change to new piston rings so that it seals well.
If your coolant turned milky substance then that means your engine head gasket is leaking engine oil in coolant compartment. With this you must experience loss of power too if head gasket doesnt seal properly 100%.
Cant understand your problem corectly.
Every car fuel tank has pressure build up to push the fuel to the engine thru fuel pump. If petrol cap is opened and heard some hissing its pretty normal. Leave it open for a minute and then refill if you think its not taking more fuel. Lets the car be running when u open the fuel cap in petrol station, so that pressure can be remove faster.
i had to service my car form the Audi guys this week but had to pay for few things which is costing me bomb.
got all the oil change form enoc guys just have to get he air filter changed.
can anybody tell me how to do this by my self.
thanks
P.S i have a Audi s5 2008 year.