Complex sentence: Services are presently (May 2015) suspended due to the tunnel & station upgrade works mentioned above-they will resume once the project is complete, originally planned in October 2015 but subsequently extended to December 2015.
Split into simpler sentences: Services are presently (May 2015) suspended due to the tunnel & station upgrade works mentioned above-they will resume once the project is complete. Originally planned in October 2015 but subsequently extended to December 2015.