Bought a phone unaware it had an activation lock.

There isn't any way to bypass activation lock without the assistance of the previous owner. The only thing I can think to suggest would be to file a small claims court claim as the phone is useless.

Also see: Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Thrive509:

That sounds like a particularly disreputable "store"!

Unfortunately, you've been hit by the old adage: buyer be ware!

I don't know about the Laws, where you are, but, depending upon the Laws, you may have some legal action you may take.

As for the phone, all you can do is responsibly recycle it.

Turn it over to the police. There is a very real chance the phone is stolen.

If that's the case, the owner of the store could be charged with trafficking in stolen goods.

If nothing else, you may try telling the store that if they do not give you a refund, you will get the police involved... chances are they would like to avoid the cops sniffing around their inventory for stolen goods.

Recycle it responsibly.