Filing complaint against a BW branch

Dear Sir or Madam, I am an account holder in BW-Bank, Stuttgart, Germany, and I am writing to you because I would like to report a case of misconduct at my BW branch in the Schwabengalerie. On October 16, 2017, my brother transferred 850 Euros from his Banca Carige branch in Padua, Italy. I was expecting to receive this money by October 26th, 2017, at the latest. On October 26th 2017, when the money was not in my account, I tried to track it both in the branch and over the phone, and eventually received a call back from my BW branch on October 26th 2017 about the transaction. According to the BW-Bank, the transaction from Italy to Germany could not be completed because there was a problem with my brother's mailing address. Therefore, the BW-bank has sent the money back to the bank in Padua. To date, no money has been received by the bank in Padua, and neither my brother or I have been returned the 850 Euros. My brother followed up with his branch on more than one occasion, and they were unable to track what happened to the money in Germany. I tried again to track the money on November, 2017, and my branch now denies having received the money from Italy, and says I must contact the bank in Padua. In fact, my branch made me call the Italian bank to ask them to contact the BW bank to track the money. I did what I was asked, and the Italian bank contacted my BW branch, and my brother and I have been informed by the Italian Banak that my BW branch refuses to cooperate. At this time I would like to file a formal complaint against my BW branch, which I am prepared to take to the highest authority. My BW branch has 1) Misplaced a transfer of money, 2) Failed to provide service to me, their costumer, and 3) Provided false information, and withheld true information that is naturally, and directly related to my account. I would also like to emphasize the point that on October 26, 2017, I received a call from my BW branch confirming that the money was received from Italy, and that they would be returning it to Italy due to technical issues. Now my BW branch simply says that the person who has called me is not working there anymore, and therefore they cannot help me. This situation is an obvious breach of both authority and protocol, and a personal violation to me as a BW Bank costumer. At this time, I would ask that this issue be resolved at the earliest possible date, or that I be directed on how to make a formal complaint against my branch. Again, given the situation, I am prepared to take this matter to the highest authority required to obtain resolution. I look forward to a timely response. Thank you, Hamed Shahsavan