The phrase "a complete alternative to" is correct and usable in written English.
It can be used when discussing options or substitutes that fully replace something else.
Example: "This new software is a complete alternative to the outdated system we were using before."
Alternatives: "a full substitute for" or "an entire replacement for".
"You have to be a complete alternative to the bricks and mortar grocery store.
If this device is not as good as (or better than) the best tablet, and not a complete alternative to a laptop — who is this for?
Sure enough, after a string of acquisitions, Google now offers a complete alternative to Microsoft's entrenched Office suite of programs, all accessible through any web browser.
The second goal, Mr. Nelson continued, was, by following those normal procedures, to allow "much debate, many amendments and even an opportunity to consider a complete alternative to the new bill offered by Senate Majority Leader Harry Reid".
Cover-Time Planning (CTP) is a complete alternative to Materials Requirements Planning (MRP).
It, therefore, cannot be viewed as a complete alternative to captive-breeding/rearing.
Kenrick notes that the album is a more complete alternative to the original cast album.
Nevertheless, and here is where Cassirer diverges from most of the analytic tradition, this modern theory of the concept only provides us with a genuine and complete alternative to Aristotelian abstractionism and philosophical empiricism when it is embedded within the genetic conception of knowledge.
The WePad may be the most complete alternative to the iPad with Linux at the core and access to the Android Marketplace.
Musette was a popular urban style as rich in its way as Chicago blues or Argentinean tango, a complete alternative musical culture, a kind of marsupial jazz, driving and complex.
