<human>: Give me a shortened version of the text

Not sure if this is the right subreddit for this, but I need some advice. My fiance and I got a ring in October. We were taking a while agreeing on the payment and the jewelers pushed back payments a month to help us(from Dec to Jan). On the receipt it says "First Payments due December" but it's crossed out with a pen and "January" is hand written beside it with the amount.  

We kept getting calls this week that we were past our due date and so I called back. The woman(who was there when I got the ring) told me that I have to pay the payment for Dec, Jan AND the interest in Jan. This means that I have to pay around $700 instead of the $400 that was AGREED UPON IN THE STORE. My fiance is furious and wants to return the ring and go somewhere else.  

If we go that route, is it possible to take that ring(before we return it) into another jeweler and say "Hey, we were thinking about returning this ring because those guys suck. Do you have something that looks like it and at a similar price? If not, I'll keep this one." Sort of like... using the old ring as leverage? My fiance thinks its a stupid idea and won't work. I want to know if he is right. What do you think?
  
RING:
<bot>: Current jewler screwing us over with payments. Before we return it, can I use it as leverage at another store?