Magento MatrixRate - How to add surcharge fees based on weight?

I'm using WebShopApps - MatrixRates to calculate my shipping fees and it works great. I just need to add a surcharge price based on weight on shipping that weight more than 50kg. To do this I need to edit the MatrixRate's model but I'm not so comfortable with magento. Does anyone have any advice/suggestion?

tnx

Solution

Why would you need to edit the module's model? You would just add a line item in the import CSV with a minimum weight of 50000 (assuming you are using grams) and include the surcharge in with the shipping price for that weight increment and any above it.

I've included a screenshot of one of my Matrix Rates tables, if I needed to do what you are suggesting I'd just add a line with a Weight >= of 50000.

enter image description here