Buy Shipping 'Letter' price issue

I’ve moved my letters over from C&D to Amazon Buy shipping due to the recent changes, my rate is wrong though but it’s the only one that is so my Royal Mail Account is definitely linked. I’m guessing it’s the wrong code but I can’t see anyway in Amazon to get it to pick the right letter rate.

On C&D I use BPL2 and is 56p, on Royal Mail it’s 68p, nothing to do with VAT as it’s exempt - unsure if I try and get this sorted with Royal Mail or Amazon or if there’s nothing I can do about it and need to suck up the higher rate

Thanks in advance!