United Bulgarian Bank issued the following announcement on Aug. 1.

• Since early August, all UBB customers already have IBAN account numbers containing the name of the merged bank - UBBS. This necessitates a change referring only to the customers of the former CIBANK, which united with UBB in early February. It is completely technical and in no way affects their accounts or related banking products and services.
  
  For convenience, their current IBANs will remain valid until the end of December 2018 to allow them sufficient time to inform their employers, partners, contractors and institutions.
  
  Information about their new account numbers can be obtained at a convenient UBB branch or from the IBAN specially designed to convert the corporate website of the bank. The web tool is available  here, and merger information can be found, as well as additional explanations for this change. New account numbers will not be provided by phone to avoid errors.
  
  For personal assistance of each client, the Contact Center of the bank team is available at 0 700 117 17 or * 7171 (for mobile operators).

Original source can be found here.