My landlord is refusing to fix heat in one room and will not put heat into a bedroom. They are willing to give us a plug in heater. Can I with hold rent till this is done. We live in mass.

You can try. I'm not sure that it's a legal tactic but if you advise your landlord (in writing) that you're withholding rent until he fixes your heating issues he may decide that it's easier to just fix them rather than fight with you over withheld rent, especially if you've been good pay in the past.

We live in mass. And since we moved in she keeps giving us the run around and now she is saying the system will need to be rerun and she can't afford to do it meanwhile our heat bill is going through the roof because the house is very old

She might be telling you the truth. She can't afford to have it done right now. What kind of heat do you use for the rooms that have heat in them? Gas is more expensive than electric where I live. I had a landlady who did not buy me heaters, but she paid the electric bill.

A different landlady discussed with me insulating the attic myself after constant problems with an old uninsulated house. I wanted to do a super job and put in R-30 with no labor charge, but she didn't like the price.She ended up having her son do it, cheap, thin insulation, but it really helped.

Insulate or move I frequently say. Find out what the utility bills have been for the past few years (if possible) before signing the lease. I rented for 20 plus years and met many landlords who gave me the run around. Work with her, she is human.

Well of course if there was no heat in the bedroom when you moved in
( no duct works and the such) many older homes ( I know of a lot of two storeis) that don't have heat upsais but the heat from down stairs goes up to heat the upstairs, this is very very common in the much older homes.

So asking for a heat duct to be ran where there was no heat when you accepted the house may or may not be a reasonable issue.

And at least short term the space heater will be some heat,

So all withholding rent may do is ruin your credit rating if she reports you for unpaid rents, and get you evicted, I guess it iis a matter of who is willing to give in first.

You can't just arbitrarily withhold rent without first going through the proper legal procedures. Most states require you send a list of problems/repairs to your landlord, certified/return receipt requested. If this fails you will need to go the court to set up an escrow account with the clerk. Your monthly rental payments shall deposited in this account until the landlord remedies the issues(s).