Vauxhall Astra engine cut out then smelt burning once car had been driven and a piercing whistle noise

Checked coolant level ?

Watch it,s not your starter motor that's jamming on due to faulty ignition switch,as they are plastic and common for faulting and ignition lock sticking causing same.

The smell could be an overheating engine if coolant level down and could also be the whistling noise from possibly the coolant header tank .

Car had been running fine providing there was always more than a quarter of a tank of fuel in (had it at garage on diagnostic and couldnt locate any fault and was advised to keep eye on it) however, yesterday when on motorway warning light came on which stayed yellow which related to emmission fault stating had reached its limit, it remained on throughout driving but the car wouldnt go above 65 70 felt it struggled when I attempted to overtake. Spoke to a pal that used to be a mechanic and he had said it could be the lumber on exhaust so I took it to Kwik fir left the car with them and when I went to collect they said nothing wrong with exhaust and think its the sensor in that its not telling the car how much fuel to pump through which makes sense but they couldnt fix it there and then. Drove to local garage and they said nah think its the coil pack but the owner of the garage came out and said there could be something wrong with the fuel pump and a change of filter may sort it. Car is now showing in sp which is due service so the garage think that if they change the filter and do a complete service it could rectify the fault. Ive booked it in but when I reversed the car last night it was making a noise and vibrating seems worse in reverse than gear.Any sugestions as I could end up spending loads of cash and no further forward.