Formal letter. Does it sound natural? What about the grammar? Dear Sir/Madam, My tickets haven’t been received on the address in Germany yet. On the other hand, Deutsche post claims/insists on the opposite. On the e-receipt (tracking number RGXXXXXXXXXDE110) only the date of receiving(4.08.14) and some signature/signatures are visible, BUT there's no name and surname of the postman nor of the person who received the parcel/letter.Deutsche post refuses to provide me more information saying the case is closed !?! As a sender,could you, please, start an investigation and contact Deutsche post using the form of investigation of a missing letter/parcel on their site? Do you have any other idea how this issue could be solved? Looking forward to hearing from you,