Fathead bought one for $90 then they cut the price to $45, but refused to adjust the cost. do not buy! Internet

I've never dealt with the Fathead company and have no stake one way or the other, but what you've described isn't a rip-off.  You agreed to the $90 price when you purchased the item.  It's as simple as that.  Just because it went on sale 2 days later doesn't change this fact.  There's a lack of understanding on your part with this (or perhaps bitterness because you didn't benefit from the sale).

Clearly they can't adjust your price, because if they did that for you they'd have to do it for anyone else.  Which opens up a completely new can of worms.  What they wanted you to do was return your original item so that the first $90 transaction would be essentially voided.  Then, after that you could have partaken in the 50% off sale.  Is it tedious? Yes. But it makes sense.  And a sale is just that, a limited period of time when an item is on sale.  So say for example something is normal price on the 8th, and then on sale on the 9th.  If you purchased it on the 8th, it's not a part of the sale.   It's pretty cut and dry.  

So to say that the company is bad or a rip off because you can't grasp or accept a simple concept, is completely unreasonable.  

As for the Customer Service Rep, I can't comment too much since I didn't hear the conversation, but you can always ask for a Supervisor.  But again, you're in the wrong on the primary issue so the Customer Service complaint becomes a moot point.