Yaris won't start properly/reliably

[lith89]

Hey - First time posting here, as well as car forums in general so appreciate the help.

Took Yaris (2006 manual) in for a service a couple weeks ago, and in the service had the fuel filter changed. Got the car back after the service and it ran well but stunk of fuel (awfully strong, partner and I felt a bit sick from it). Anyway, we took the car back in the next day as it hadn't gone away and turns out they hadn't, if I remember right, put a cap back on correctly. So took the car home, next day the fuel smell came back and the car was now having trouble starting. It would "crank" but not start on the first go, requiring up to 3 attempts to start. So we took the car back in again and they said they hadn't put the fuel pump back together properly (something about an O ring?) and they had fixed that, though they weren't sure exactly if that was causing the problems with the car starting. So, again, we take the car back and the fuel smell is now gone but the car is really struggling to start every now and then (maybe every second time we use the car it takes a couple tries to get the car to start). We replaced the battery, just in case it was that, turns out it wasn't. Called them about this, they said there not sure what's wrong. One other thing we've noticed since the service is - when we refuel and fill the car the meter isn't saying full, it's showing one bar under, something it hasn't done before. So I've kinda just given up for now, with work being busy taking it back in this often is a little bit difficult.

These are all new problems that popped up after being serviced, car's been remarkably reliable for the last 10 years.

TL;DR -

Took car in for service (included fuel filter change).
Took car back as car stank of fuel when driven.
They said "cap" wasn't put on properly in service, now fixed.
After driving around a bit we notice fuel smell is back and now the car won't start properly (cranks but won't start all the time).
So, we take the car back in. They said pump wasn't put back together properly (O ring?).
After taking the car back and driving around the car still won't start properly/reliably, and fuel meter doesn't show full when filled (at this point the fuel smell is gone).
We replaced the battery just in case it was that, didn't help with anything.

Any suggestions/advice would be greatly appreciated.