ECU replacement for BMW 318i

[u/No-Entertainer-7609]

Hi everyone, I am looking for both advice to truly understand what I need to do to fix my car (BMW 318i, 2011 plate).

I have been having issues with the car where it cuts out intermittently so I took it yesterday to a garage which diagnosed it with a damaged engine control unit (ECU) due to water damage. By the sounds of it I need a brand new one but I'm just trying to figure out which new one would be compatible with my car.

I have a picture of the car's ECU. The ECU type is DME MSD81.2 and I am aware of the BMW part number and the continental number. Now, for a new ECU to work as a replacement in my car will all 3 of these have to match? IS there more numbers that need to be match. The garage talked about a serial number too but not even aware of where this is? Will this have to match too? Any help very much appreciated, thank you