E90 320i rear driver side seatbelt replacement

[livruff]

Long story short, someone stole my son's car seat from the rear driver side of my car and kindly cut the seat belt too. Ordered what I thought would be the right seat belt replacement, mechanic says it doesn't fit. So could someone please tell me how I can make sure I absolutely order the right seat belt for my car. I don't want to keep ordering parts and its not the right one, need to get this sorted asap because one of my children has to now sit in the passenger seat which I loathe from a safety point of view. I have the actual seat belt part but it has so many numbers on it and I'm not sure which is the actual part number. Thanks

[Badgerboy]

I'm sure a good start would be to pop your VIN into realoem.com.

That should have the build spec of your car, and you can navigate to the part in question via their parts diagrams.

[livruff]

Pop my what into the what now? Sorry as you can tell, I know nothing about cars. So this VIN number, where do I find it?

[livruff]

Actually I found it on my V5 form, thanks Badgerboy, your info was very helpful I found the part number and somewhere that sells it too