Rebooking Flights

Hi there,
I had my original flight booked for the 5th June 2020 Gatwick to Montego Bay VS65 Upper Class. This was re booked for the 21 August as my wife had not used any of her holidays and she was going to lose them if they were not taken before 1 sept 2020. Virgin did not charge us anything to change the flight, even thought it was a more expensive flight. This second date also looks unlikely and we may have to push back the date again.
Will Virgin charge us to change the date again?
The VS65 flight was originally a 747, what aircraft will now be used on this route?
Thanks for any info
I had my original flight booked for the 5th June 2020 Gatwick to Montego Bay VS65 Upper Class. This was re booked for the 21 August as my wife had not used any of her holidays and she was going to lose them if they were not taken before 1 sept 2020. Virgin did not charge us anything to change the flight, even thought it was a more expensive flight. This second date also looks unlikely and we may have to push back the date again.
Will Virgin charge us to change the date again?
The VS65 flight was originally a 747, what aircraft will now be used on this route?
Thanks for any info