2011 mustang Airlift suspension clunk 

After 4 months of riding on airlift suspension I started getting a loud clunk from the strut mounts. Contacted the company and they sent me a new strut and I sent the old one back. Installed the new strut and the noise went away. They later called back and told me there was nothing wrong with it and charged me. I sent them this video prior and they told me they couldn't hear anything