Contractor is dead slow in carrying out the work and asks for excess amount to continue the work

I have given a turnkey contract to build a 3 storied house in my name.. Project was started in February 2nd week and till now only the ground floor roofing work is in progress. The total cost of the project is 55lacs divided Into 10 stages.. A total of 21 lacs has been paid to the contractor even though only the 4th stage has just been started.. One of the stages included wood purchase charges for which an amount of 5.5lacs was paid but till now the contractor has not shown the wood and when asked he said its being worked upon at a different location. The work has been dead slow and now the contractor says he needs more money in advance to complete the current stage as he has some financial problem..another issue is he still hasnt got me the building permit and when asked he gives some lame excuses. I would like to switch over to another contractor but not before getting back the excess amount paid till now including that of wood. How do I go about this in either making the contractor work faster with permit or switch over?