What "regulations" force cc cos. to have settlement funds in 90 days

I have 3 cards I am currently attempting to settle. BOA is the first one - my first offer 2 mos ago from them was $3400 which I had to decline because I only have $1200 to work with. I told them I am also attempting to settle with 2 other creditors. Yesterday, they called after receiving my settlement letter and said the lowest they could go was $2800 (charge-off will not be until next mo.). I told them the only way I could do that would be to make $400/mo pmts, which would take 7 mos. The rep said settlements have to be paid w/in 90 days and that they would be able to settle a lot more accts if they were able to set up pmts for longer than that. He said he thought the govt regulated this but was very vague and could not tell me anything else. If credit card companies can do hardship pgms over a 5-yr 60-mo. period, why can't they do settlements for longer than 90 days - like, say 4-6 mos.? Can anyone tell me what specific regulation(s) governs the time period that settlement funds have to be received? I know this has been asked before but I cannot find where anyone actually was able to pinpoint a rule or regulation to look at.