Premium Shipping amidst the Pandemic

Amazon have removed the Premium shipping option from my listings as my on time delivery rate has sunk too low.
I send (as standard) all my orders using Royal Mail 48 and everything that is ordered before 2pm is sent the same day. So unless I start to send using RM 24 I cant do anything better.
You would think with the current situation with Covid, and its effect on delivery times, Amazon would lower the on time metric. I have had queries from customers asking if I have a faster delivery option but I cant offer it so Amazon (and not me) are disappointing some customers.
Even if I did start to use RM24 instead of RM48 I doubt enough orders would be delivered on time to get the on time metric above the 96% required by Amazon so I can offer Premium shipping.