Honestly, I think stealing is a strong word...
As a business owner, I honor the price that was quoted even if cost of materials go up or labor takes longer than expected. Ultimately this affects my bottem line but my clients are not stealing from me.
As a supervisor in a large retail chain, I have honored: expired sale signs, mismarked products, expired coupons, coupons that have already been used and given guests discounts because they were not getting the service/product they expected (whether I agreed with them or not).
In business & life you win some & you loose some. I don't think OP was out to get anyone...She happened to "win one" today and the store happened to "loose one" today.
Moving on to find pixie dust... Have a good night!