Can a debt be charged off while on chapter 13?

What is the name of your state? PA
This debt was listed on the bankruptcy and the company never filed any claims for the creditor's meeting. They charged off the account a month after the creditors meeting , and two months later filed for foreclosure but later on they dismissed it. We have been making regular payments and in the meantime another company bought out the mortgage company ( not the loan ) and they never notified us of anything, until I found out last december , they sid they couldn't contact us because they would be violating the automatic stay laws. They have called us at home every month even if the payment was only a day late, they violated the automatic stay, however today I got a letter notifying us that our loan has been charged off on their systems as a non-performing loan as of 8/7/2003.
Now they are also threatening to foreclose, but again they have had no problem taking payments for over 3 years.
There's a statement in bold that says:
" To the extent your obligations have been discharged , dismissed, or are subject to an automatic stay of a bankruptcy order under tittle 11 of the United States Code, this notice is for compliance and informational purposes only and does not constitute a demand for payment or any attempt to collect any such obligation"

We just recently discovered that the account was first charged off on 10/1999 while checking our credit report, only that time was done by the company before it was bought out , now it seems they charged it off for the second time with the second company. Someone please tell me, is this a common practice? Is this legal?

bump, anyone know??