Void Warranty : buttons

My down volume button got stock when trying to press it , i sent it to Datrepair in germany i live in denmark they told me to pay 2500 krone thats 380$ to fix it , they told me that i have an unOfficial software installed , it's of course rooted i sent mails , called the workshop to tell them what the hell they were talking about i knew that it i had installed other rom but i did install the original one before sending it back and told them they i need a proof that there were unofficial installed but they couldn't and the day after that a mail was sent to me that they wil fix it without any cost . i also told them that the software has nothing to do with buttons i could understand if the chip was burned or something else hardware were damaged becouse of the root but it just a buttons and now im waiting for it to arrive :)

what will you do in my position ? sorry for bad english