Urgent pipes upgrade issues

I have an apartment in the first level, there is an upstairs unit. The upstairs pipes burst a few years ago that caused damage to our unit, our insurance has to take of carpet and ceiling repairs, but then their pipes burst again last Thanksgiving, when the plumbing came repair them they strongly recommend that both the upstairs unit and ours pipes need to be updated since they are 40 years old. Since the two units pipes are connected, it is pointless if we only do our part, the upstairs need to upgrade as well. The upstairs unit owner refused to put money to upgrade their pipes. But recently in the past couple of weeks, this happened again- the upstairs pipes burst again. I went to ask the upstairs unit, the owner is very cold and rude, and refused. 

We have a HOA but the HOA seems not really rule over the individual owner, the HOA committee chair and president both convince the upstairs unit owner, but she seems don't listen to anyone. Any suggestions?