The lil bugger is
only 4 months old. Sounds like he's got you buffaloed.
In your shoes... I'd toss the all rope halter and put a good rope/nylon halter with a CHAIN on him. He needs to get rid of the attitude and the chain will help you do that. Then, I'd leave him tied several hours morning and night, with the rope tied about back-level and with about 18" of slack. Alternately, take him into your yard and stake him out with about 10-15' of rope. You'd be surprised how quick a calf will start minding when he's dumped himself end over end a few times, and after he's hit the end of the rope enough times his jaw will be sore and he'll be more willing to cooperate. (Now that I think about it, I'd suggest staking him out rather than tying him to a post -- it sounds as if he's learned enough at the post already and he needs to move to the next level.)
If he tries charging you, a stout stick or whip will teach him to stay out of your space. Generally I find that calves who appear to "charge" usually are just lungers -- when they finally decide they're going to take a step forward they take a BIG one.
However, that's unacceptable behavior. Keep in mind that "tame" does not equal "halter broke", but I've had some very well halter broke calves that were wild. In fact, the better halter broke calves were actually a little wary; it seems if they get too tame it's hard to get them to do anything.
The chain on the halter is there for a reason -- use it. Carry a whip or a stick and use it too if necessary. Tell him he's going to shape up, insist that he mind his manners, and in the meantime, leave him staked out in the yard so he can learn some lessons on his own. Worry more about him obeying than getting him "tame."
Best of luck.