Notice period Recovery amount

Hi, My Company is a start up and I have duly served a notice period of 1 month as directed by my Manager and the new company agrees on buying out the rest of my notice period i.e 2 months. 1. But the startup has calculated the notice period recovery amount on the basis of Gross salary and also added 2 months Conveyance allowance, which they used to pay only when the employee is present in office but I have left the company still they are charging the conveyance amount in notice period recovery amount from me. 2. Old company(startup) has calculated my Leave encashment on the basis of Basic amount and the notice period recovery amount on the basis of GROSS Salary. Now, the new company is asking me to talk to them to reduce the Recovery amount by Calculating it on the basis of Basic Pay. What should I do as I had been really chasing the old Company for mere F&F for a long time and now finally that I have received the document, there are so many issues with that. What Should I do?