Rochester not honoring warranty

I purchased a base and matrass. On the matrass it is embroided that there is a 15 year warranty. The embroiding is " Rochester Revive Matriarch 15 years". This matrass was only sold in 2015. The inside has now separated at the nested pockets. I have contacted the store (Northgate) where the purchase was made but they are unable to find the transaction. I have moved twice over the years and can not find my receipt. Rochester is now refusing assistance. I have attached the specific matrass details as per there website to show that it was only sold in 2015 so there is no way the matrass can be out of the warranty period. Their name is embroided on the matrass so it could not have purchased from any other company. How do I resolve this matter?