Unum wants me to give them my SSA money for a month I didn’t receive it. Do I have recourse?

UNUM was prompt with providing our benefits when my husband went on disability, but then proceeded to have us pay back money after SSA started to cover him, which is “in the contract.” My question is this, SSA does not pay until the fourth wednesday of the following month after awarded. So we were awarded SSA for October for both my husband and daughter but not sent a check until late November. UNUM has us paying them back for the month of October bc of the date SSA said we were eligible. In short we are having to pay them back for a month we never received. Is there recourse for this? The SSA payment schedule is the same schedule since 1997. UNUM knows how SSA pays.