Couple of things.

As you booked a VS operated flight and VS changed schedule, they under EC261 (still in effect like most EU law in UK, commonlycalled UK261 when referringto UK) are responsible for costs incurred. They will have to pay for hotels/meals for any added overnight.

You need to contact DL during weekday and ask for Joint venture support desk. They can contact VS.

If there is award availability they can rebook via AF/KL. They can't force availability on partners.