Complex sentence: At his accession, Nnewi had a very small and miniature one room postal agency, but that has since developed into a full-fledged modern postal business system equipped with modern international communication technology.
Split into simpler sentences: At his accession Nnewi had a very small and miniature one room postal agency. But that has since developed into a full-fledged modern postal business system equipped with modern international communication technology.