Rent/roommates issue

So when my roommates and I renewed our lease we got a one time concession of $300 off of rent. Well something went wrong with the online site and that 300 off was never removed. Now while it is the rental property’s fault they have in writing on the lease and in emails it is supposed to be for one month only. So even though it’s their wrong they have every right to make us pay it back.

I keep telling my roommates we have to bring it up and get it resolved but they keep pushing it off. I know it will be harder to pay back the more we wait and it could even make it harder to get a place in the future. It’s been the 3rd month this has gone by (so by this point we each owe $300)

What do I do? I’m afraid if I do something about it myself they’ll just be pissed and I’m not really in a position where I can move out. But also the longer this goes on the harder it will bite us in the ass later.