Citroën C2 Driver side door won't unlock

[Lilam691]

So got to my car in works car park to find that the driver side door hadn't shut fully and got the the seat belt jammed in it. When I tried unlocking the car using the remote locking, the driver side door wouldn't open. Tried using the key in the door, still wouldn't open. The passenger side opens fine and I can open the driver side door from the inside. What could be the issue? What's the fix? TIA!