ECU problem

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I received an e-mail from the Audi dealer on Friday.
They have changed the fuel pump, but it wasn't faulty.

Turns out it is the ECU: 4D0997557EX
Which was filled with water according to Audi. And they weren't able to locate a used unit in Sweden.

I haven't talked with them yet. As I arrived back home late last night. Was gone for two weeks working in Norway.

So what do I do now? I looked for the ECU on 8parts shop, but didn't find any.
Do you recommend I send it to
http://www.ecu-repairs.com/engine-ecu-repairs/audi ?

Oh! And does the ECU have to have an exact match in the last two letters?
I see https://trshop.audi.de/konakart/Quic...57EX&x=11&y=13 has other variations.