This is the resonse I received from the seller performance team
Greetings from Amazon Seller support. This is Jyoti and I have been assigned your case today.
It was a pleasure talking to you.
I understand your concern regarding Elimination of First Class Mail shipping option for shipping prime orders. Please accept my sincere apologies for the inconvenience caused to you in this regard.
As per our phone conversation, you can still use USPS First Class Package Service® to ship your standard SFP orders.
As informed to you we are taking this action to maintain the Prime delivery promise to our customers. We will continue to work with USPS to ensure that First Class Package Service® can meet the Prime delivery promise, and we will notify you when it is available again for SFP premium orders.
Additionally Amazon has integrated carriers for the benefit of the buyers, Amazon cannot guarantee the time on which the carries will offer two day shipping options. The reason being carriers are different entity outside Amazon.
In such scenario, you can fulfill the order using one of the integrators which are currently supported by our system.
Using the integrators there is chance of you getting discounted prices than our platform
Below are the supported shipping integrators which are supported by our system:
•M2E Pro - Amazon Magento Integration
•SolidShip by Solid Commerce
You can confirm the same through the below link:
Terms and conditions
Before a seller can use any application that uses the Merchant Fulfillment service to fulfill Prime orders, they need to:
1.Review and accept the terms and conditions of the Buy Shipping Services program.
2.Review and accept the terms and conditions of any carrier that they want to purchase shipping from.
Sellers can review and accept terms and conditions on the Manage Shipping Services page through the below link:
All you need to do is create an account in one of the shipping integrators and then link you selling account to it. Once you agree all the terms and conditions you can go ahead and ship your orders through them.
Your understanding in this regard is highly appreciated.