In May 2015, unit 375301 was moved from Ramsgate Depot to Derby Litchurch Lane Works for a full refurbishment. On 16 May 2015, it was returned to the Kent depot wearing a new livery, similar to, but not based on the 'Highspeed' livery carried by the high speed Class 395 EMU, with a more vibrant shade of blue on the saloon doors and bolder stripes to highlight First Class and Disabled areas. Internally, the unit has received new carpets and lino flooring, new table top covers and the grab poles, side panels and table legs have been re-powder coated. The existing seat covers have been retained, but were dry cleaned to provide a brighter, cleaner interior. This work will also involve combining the two separate First Class sections on four car units into one section in the end of MOSL coach. It is intended for all class 375 units to receive this refurbishment between 2015 and 2018. The original plan was for the first 50 units (375/3s, 375/6s and 375/7s) to be refurbished at Bombardier in Derby and then the remaining units would be transferred for refurbishment at Bombardier Ilford. This plan did not go ahead and the 375/8s and 375/9s were sent to Derby. On 19 September 2015 the last 375/3 unit no 375310 went to Derby for refurbishment. The following week on 26 September the first 375/6 went to Derby for refurbishment. The final 375 to receive the refurbishment and gain the new blue Southestern livery was 375 920, which was returned to Ramsgate depot on 28 April 2018. Electrostars also work the following outer suburban Southeastern routes interchangeably with Class 465/9 units:   Class 375/3 units started operating services on the Medway Valley Line from May 2012 to January 2016, and then from September 2016 to present day, with the exception of a few high-speed services from London St Pancras during peak hours. 4-car Class 375s and Class 466 Networkers occasionally appear as well as a substitute unit. When the sea wall between Dover Priory and Folkestone Central collapsed, Class 466 Networkers covered the services along the route until it was repaired in September 2016, with the Class 375/3s being used as a shuttle service between Ramsgate and Dover Priory via Sandwich and Deal. From 16 November 2019, Class 375/3 units have replaced the Class 466 Networkers, initially due to power issues with the 2-car units on the line, but ultimately to conform to the 2020 disabled access regulations.