The deposit takes other amounts

Hello, I am using your plugin to collect a 350-euro deposit and the rest is already paid in person. However, in the cart I also have an additional value of 180 euros that all the products have How much am I going to pay for the product, it charges me the 350 deposit plus the 180 fee. I would like it to be only the 350 deposit, the rest I pay directly to the seller…