We're all assuming a lot here. We don't know what type of loan she received,Conv,FHA both have different allotment of seller closing cost contribution. We also don't know if the Agent knew which loan she received. For all we know she just went there with a Pre-Approval for X amount. If she went there with a Pre-Approval we don't even know if the lender discussed this aspect.
NOW once the deal was struck ,house found,price negotiated, and the lender is writing up the deal says Oh O this cannot fly! So she approached the Agent don't know if the buyer was contacted stating that. So whats at beef here IMO is that the seller is now trying to renig on the amount of closing costs agreed on now wants the money in her or his purse.
So I'd push it call their bluff and say pony up the difference so I don't have to come out of pocket on the purchase price of the home or I'm going to walk. IMO there is no fraud ,if I'm reading this correct,just that the seller wants the money and of course the higher the selling price the more commission the agent receives.
The rest of the mess ,still in the home,is mute,not important unless they come to a agreed purchase price now. I'm sure the seller wants the money ,who wouldn't ,but they need to weigh the option of having to start all over again and lets this buyer walk.