Can it really be the ECU?

[AndrewinBarnet]

We live in north London and while on a trip to Cornwall our Aygo (2007) was scraped on the underside going over an uneven surface. It cut out but started again and all seemed fine. 

However, half a mile down the road it cut out and would not start again. StartRescue were called who couldn't fix it roadside but said they suspected a pinched fuel line (the engine was turning over but not even trying to start). We were towed to the nearest garage with the hope they'd fix it before we had to head back. 

They reported no DTCs so began a methodical inspection, initially deciding it was a camshaft or camshaft sensor problem and replaced these. Apparently (by this time we are back in London so only relying on their say-so) the car initially started again but stoped. So they brought in their electrician who did a full inspection and not found anything but has suggested a fault with the ECU. 

It seems too much of a coincidence that the scrape has nothing to do with the car cutting out half a mile later? Does all this sound plausible?

The car has a full service history and was serviced within the last month but has had a few problems, most recently after the service where something that looks like it fed into the engine on the righthand side (I don't know about cars) had been left loose, causing it to stutter and cut out.

I'm really at a loss at the moment, it's 250 miles away. Do I give the go-ahead for yet another person to check the ECU (cost? £150?) can the ECU likely be repaired or is it a replacement? Is that basically a write-off? URGH!