Tax arrangements

Hi all, I was a first time independent last year. I was a bit niavie and used an employment agency that got me an accountant etc to do VAT. The accountant however turned out to be very stupid and I feel I'll owe a lot more taxes than he told me and that I budgeted for. We have a meeting with an account whom we trust through our family to go over everything next week, but worst case scenario - How do the Belgian work out tax payment plans? I think we'll owe about 10.000 more than we budgeted for according to the last accountant. We don't have that much in savings and can't sell anything of that value. I moved back to permanent employment this month so we both make modest incomes now. We can't afford to take a loan out or pay much a month... Its a bad scenario and we're looking to sell a car, but would take a loss as its newer, can't sell the house , furniture isn't worth that much. We don't want to cheat them, but are afraid they won't accept modest payments; Anyone have experience?