Cook WearhouseShed Sold me a lemon and wont honor lifetime warranty Internet

I bought a shed with a lifetime warranty. I still have the original contract. They have had to come out twice to replace shingles. The lock broke and they made me purchase a new lock. (I assumed it would be covered under the lifetime warranty) Now the siding on the shed is decaying and buckling. I reported it to Cook sheds. They claim it is NOT covered under the lifetime warranty. They also informed me that the shed needed to be treated every couple years. I was never told that, nor is it in the contract. When I filed a complaint with the BBB they resorted to falsehoods about me and the shed. My shed is a peice of junk. I feel I was deceived about the lifetime warranty.