Learn German: Bei Fragen wenden Sie sich bitte an das Büro. - If you have questions please turn to the office.

Using bei with a noun is a common, elegant way to express a condition in German without needing a full wenn (if) clause. Bei Fragen literally means 'in case of questions' and is standard in formal instructions.

What is the exact meaning of wenden here?

The reflexive verb sich wenden an literally means 'to turn oneself to.' In this professional context, it translates to 'to contact' or 'to reach out to' someone for help, information, or support.

Why is it an das Büro (accusative) and not an dem Büro (dative)?

With the verb sich wenden, you are directing your communication towards a specific target. Because there is a metaphorical sense of movement or direction toward that target, the two-way preposition an requires the accusative case.

Why doesn't this polite command start with the verb, such as Wenden Sie sich?

While polite requests often start directly with the verb, putting an emphasized phrase like Bei Fragen first is perfectly fine. When you do this, standard declarative word order takes over: the verb must be in the second position, pushing the subject Sie into the third position.