Michelin review: tire warranty not honored

2014 mercedes ex
purchased two tires 0n 03/06/2017 invoice [protected] odometer 28528

purchased two more tires on 02/05/2018 invoice [protected] odometer 36432

0n 02/05/2018 tire centre after only 8000 miles by error replaced still good tires purchased on 03/.06/2017. They were expected to replace older worn out tires

Car now at 48k odometer has in front still good tires
At the back car has OEM tires which are worn out and of course has numbers whichare not costco numbers

We purchased total of 4 new tires from COSTCO and because of error on part of Tire center they are not honoring the Warranty
We have only one vehicle with this tire size.
Proof of 4 new tires bought from Costco should be adequate proof
Disappointed customer
Sudhish aggarwal
904 stonecutter ct
raleigh Nc 27614
tel no [protected]