I owe the college for cles over 10 years old and now want to take cles. Do I have to pay?

I took two cles in 1999, but dropped them (I paid for them, but dropped after the date for a refund). Apparently, at some point in time they erroneously reclified me as a non-resident student (I've lived in California where I took the cles since 1995). It is possible they sent me doentation about this change and I never got it because I separated from my husband and moved which is why I had to drop the cles. So now I want to go back to school to become a psychiatric technician and this debt for over $800 pops up and I'm told I can't register till I pay it. I went to the school and they said I can fix the classification with certain doentation, so I provided it. Two days later I received email saying that the doentation I provided was inadequate and they want more. I already gave them 2 years of tax returns, my son's birth certificate showing I had him here, my voter registration info dating all the way back to 1996, copies of licenses I hold here. All of these are things they said were adequate. Now they say they need 2 more years of tax returns that are over 10 years old and I can't find. The IRS and franchise tax board don't always even keep these records that long...I called looking for copies. Or they said I can provide copies of my bank statements from 1998, 1999 and a current bank statement as long as they're the same account. Well, of course it's not the same account. I held an account with my husband in 1998 and 1999. I feel they're trying to jerk me around and make it impossible to fix this. The "debt" is over 10 years old and I know the statute of limitations on debts in California is 4 years, but I don't know the extent of that. Meaning, I don't know if they can deny service due to a debt that old. I'm not trying to be a deadbeat, I just don't want to have to pay for their mistake.