My Mac Air 11.6 Keyboard is HAUNTED!

Question

I asked a question about this a few days ago ... "My Mac Air Keyboard is Krazy!" ... but didn't get a nibble.
Now I have some more information. The trackpad and most of the control keys are fine.  And I'm writing this on an external keyboard, so all of the smarts are working ...
I opened the virtual keyboard and realised it's LIKE THE CONTROL KEYS ARE ALWAYS PRESSED!  I'm getting the symbols and alternate characters you get when you press shift and option, etc
I've restarted, reinstalled, soft repaired and everything, but it is just the same.
Is it just a matter of a keyboard replacement?  Is that costly?  Should I just hand out at the Genius Bar if there's no geniuses here?
PLEASE HELP!  IT'S MY 18 YEAR OLD DAUGHTER'S MAC AIR AND SHE'S ON MY CASE IN A BIG WAY!  SHE'S A GENERATION ZEE, SO IT'S ALL ABOUT THE KEYBOARD CONNECTION!
HERE IS MY ORIGINAL POST:
OK, My name is Randall and I'm a Mac Head ... I have been using since 1986. Oh, sorry ... wrong support group ...
The keyboard on my Macbook Air 11.6 has gone crazy. Like all of the sudden. All text buttons started coming up as random symbols.  Something would just open and download odd things and do odd shortcuts.
Tried everything ... recovery, rebooting PRAM reset, reinstall of Mavericks and Yosemite ... most control, shift and the power buttons work fine ... with an external keyboard, it works fine.  It's just that the type is all jibberish.
Help me before I go nuts!  I don't want an expensive repair or have a techie tell me it is fakacktah ...
Dying here!  (I had to send this on a f*****g ASUS!)

Answer 1

The unit likely should be taken to an authorized service provider where
a specialist in those models can test/diagnose the problem and then
suggest the methods and estimate cost to cure the condition.
An Apple Store with Genius section could be helpful, if available, & should
you be able to get an appointment for time allocation to discuss the matter.
A Genius or in-store specialist usually can perform tests & diagnose issues.
Given the unit is going on 5(?) years, it may be in need of other replacements
while it is open. Items that wear out, such as they are. A battery, for example.
They may have a flat rate repair fee where for, say, $300 they fix stuff. And
the more that can be lumped into that rate, the better the cost factor.
Or perhaps it may be time to look into another MacBook Pro or Air model.
There are some late model units in Refurbished/Clearance in online Store.
Be sure to predict the use pattern of a new non-user upgradeable model
and purchase sufficient configuration specifications, looking ahead.
Hopefully the issue is cost effective to resolve.
Good luck & happy computing!