Error: "Your SKU's count is more than 1000" and a prompt to upgrade the plan.
However, you only have lesser FBA SKUs in your Shopify store.
It seems that you have total active SKUs synced from Shopify more than 1000 SKUs, however you have the actual FBA SKUs less than 1000. (This SKUs count could be different as per your respective
billing plans.)
In such case, non-Amazon SKUs / unlinked SKUs can be archived in our app to minimize the total SKUs numbers.
So since you are locked out at screen, so the first step is :
1. Upgrade to a plan and once done you can start archiving the SKUs as mentioned above.
2. After doing so, you can downgrade the plan to the one you desired for, same day.
Here you are charged always on pro rata basis only by Shopify. So, you will not be charged double / extra / additional simultaneously while switching the plans as this is usage basis.
(There is only one plan active always at a time.)