I need your guys help!

So my fiancé and I HAD two cars. A 2007 G6 and 2002 Jeep Grand Cherokee.

Both cars are in my fiancé’s fathers name because it’s the only way I can afford the insurances on both.

We have PLPD on both cars.

The Jeep was $75 a month and the G6 is $105. So $180 in total.

Here’s the dilemma: We sold the Jeep a couple months ago, and took it off the insurance, supposedly I still had to pay the $180 until this month. The insurance is due on the 18th and his step monster is saying it’s now gonna be $150 for just the car. Which makes NO sense. But my fiancé is clearly way to stupid to not think something’s a little fishy. His step mom has done this before to get more money out of us. And I want a break down from the car insurance company explaining why it’s so high. My fiancé is saying it’s not a big deal, but to me is! We can barely afford to pay our bills and if she’s making stuff up to get more money out of us I think it’s WRONG.

So tell me your opinions guys!!