bridget96, the sentence would have been correct with the addition of two commas:
"AMI’s warranty, conditions described herein, is subject to the following":
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BelM, correcting one's boss is a sticky situation! Whether to do it really depends on the circumstances. However, I will stick to the one you seem to be describing: your
company's clients are going to see a web page that may not
be exactly confidence-inspiring, and it is important enough to you that you have made repeated efforts to get it changed.

I have two ideas about what you might try: see if there is anyone who: will listen to your ideas and probably agree with them, AND--who has the ear of the boss, and get this
person to try and persuade the boss. My other one is to
write a memo to the boss (I believe it is good business practice to keep copies of any and all memos you send.) saying, first, why you're writing: that you are very concerned about xxx. Then explain why you're concerned. Lastly, offer concrete examples of changes you
think would be well-advised. This will give him something
to work from, if he's willing, and, if he's typical, he will want to make changes to your changes. But if they're still good grammar and spelling--you've won. Good luck!