I've had non-compete agreements provided to me to sign in the past, usually as part of a packet of things to sign. In each case I just pocketed them without signing them. I've never had a company come back later and demand that I sign the thing. If they don't do their diligence, I don't see why I should do it for them. In other words, just because someone puts something in front of you to sign doesn't mean you have t…
Now if only I could do that with software-enforced EULAs. You know, the things that nobody reads but generally sign away all your rights.
Send a letter via snail mail that clearly states that you disagree with their EULA but were unfortunately only made aware of the EULA after your purchase. Include a printed, revised EULA with your proposals for changes. Be reasonable in the changes you propose.
If they reply to you that they disagree with the changes, they can prohibit you from using the software or service, but then you're also entitled to a full refund, of course.
If they forget to reply, their EULA will not be enforceable.