Now official as I've just received this email from VS Trade:
REVISED- VSbulletin 007- Reprotection policy for passengers affected by our withdrawal of services to Varadero
We need to let you know that after the S17 Schedule, we will no longer operate our London Gatwick (LGW)-Varadero (VRA) service with our last flight operating on 3 September, 2017.
Customers booked on our service to and from VRA during the W17 Schedule (25 October 2017 – 30 March 2018), will automatically be reprotected onto our Havana service on the same day. Ground transportation will be available to take customers to VRA.
Customers booked to travel to and from VRA during the S18 Schedule (from 31 March 2018), will be rebooked onto the Havana service the following day. Ground transportation will be available to take customers to VRA.
You will see this changes in your customer’s booking after Saturday 12 August 2017.