I think that 'function' in the sense of a corporate function, namely Customer Services, is a valid commercial expression in this context. Common, if elegant commercial terminology. Alternatively, 'facility' or even 'place'.

A proposal. The functional, purposive sense is fully conveyed by the preposition "for" in the context.

Otherwise, my feeling is that you can also use "function", as Peter proposes; a sort of popular corporate terminology that makes them feel hip.

I think "facility" sounds too concrete; as if it was a particular building or office space.

Another suggestion may be "department", but this would only work if the "kundtjänst" in question really forms a separate department of its own.