He has to contact A1 to let them unlock it.
Without invoice you will have to pay much more.
Use one of the online contact possibilities if you cant visit an A1 shop.

I am not in Austria now .

Can I pay from my country ?

Where to contact them ?

They have live AI chat channel .

And landline phone number on A1 web site  

or via facebook and instagram

Why dont you alk your brother to do it for you?
Woultd be the esieast way.
Something seems to be wrong with your story ...

Hello, please contact us via www.a1.net/kontakt

br Jürgen

SIM lock: How can I have my cell phone unlocked?You can have the A1 SIM lock removed in any A1 shop. Please take the invoice for your cell phone purchase with you.Unlocking costs:150.00 euros (125.00 euros excl. VAT) within 12 months from the date of purchase100.00 euros (83.33 euros excluding VAT) within 13 to 24 months from the date of purchase50.00 euros (41.67 euros excl. VAT) from the 24th month from the date of purchaseWithout an invoice we charge 150.00 euros (125.00 euros excl. VAT

within 12 months