Does my tenant have the right to withhold security deposit/rent for not being able to flush toilet paper, due to old pipes?

I moved in the same time as my tenant did so I was not aware that we had plumbing issues. Are toilets backed up but I fixed the problems right away, the plumbers said we just can’t flush anything including toilet paper. We haven’t had any issues since. A few months later she is asking to change her payment due date from the 1st to the 15th. I said I would agree as long as she also pays the security deposit she owes us from a few months back. She was upset by this and now is mentioning how not being able to flush toilet paper is a inconvenience and her lawyer says she doesn’t have to pay rent till it’s fixed. I filed a claim when this first happened but the insurance refuses to give us money we are trying to fight it but it’s a long process. We used her original security deposit to pay for a month she was not able too. She agreed she would pay us the security again, as we know she’s struggling we lowered her security deposit by half. She signed and agreed to this but never complied.