Replying to Yo...binding advice (and other help) needed

Hoping someone could help me out here. Just received a cherry set of scratch fs with rossi 100 bindings from eBay, only problem is that there were supposed to be 120s on them.

I weigh 190+ and need the higher DIN, How much $$ should I ask for back? He is pulling shit from the rossi site and saying that the scratch 10 will cover up to 240 lbs. How do I explain to this guy that 10 is just not enough for me?