, CaRDiaK wrote

Can I send MS my bills if my eyes get even worse or my headaches continue?

No.

Microsoft excludes all implied warranties, including those of merchantability, fitness for a particular purpose, and non-infringement. If your local law does not allow Microsoft's exclusion of implied warranties, then any implied warranties, guarantees, or conditions last only during the term of the limited warranty and are limited as much as your local law allows. If your local law requires a longer limited warranty term, despite this agreement, then that longer term will apply, but you can recover only the remedies that are described in this agreement

http://download.microsoft.com/Documents/UseTerms/Windows_8_English_ca383862-45cf-467e-97d3-386e0e0260a6.pdf

Can I have a refund please?

Microsoft provides limited support services for properly licensed software as described at support.microsoft.com/common/international.aspx.

If you are seeking a refund, and you cannot obtain one where you acquired the software, contact Microsoft for information about Microsoft's refund policies. See microsoft.com/worldwide, or in North America, call (800) MICROSOFT or see microsoft.com/info/nareturns.htm.