What do I have to do to get Medicare to get me a walk in tub?

Have your doc write a letter which you can use to see if medicare will assist with the cost-but also do your homework and have as many companies come out and tell you about their product the iinportants are how high is the step up our was suppose to be 6 in and it was a foot also in the botton skid proff also does to have hydro jets also you need many grab bars how far do you have to step in to reach the seat if you fall in it how hard is it to take apart. Get all their promises in writing we were suppose to get a larger door to the bathroom to accomadate a w/c as promised by the salemen and did not how are you paying for it 1/2 should be held until the job is complete if there are problems who do you call are they rated with the BBB-would a w/c shower be better for the person.