summons sent to wrong address

My husbands father recently (two days ago) received a summons tucked behind his mailbox and then today a mailed copy of a summons for my husband. He has not lived at that address for almost ten years. We do owe the debt in question, no defense to that, however up until sept. of this year we were in a debt management program which this creditor was included. Due to other financial strains we were unable to finish the program. This is one of the two debts not settled. I went to a comsumer credit couselning agency and was told that we should file bankruptcy. We have been trying to save money to do just but needed to pay our property taxes and other housing expenses first. This is the first time since leaving the debt program that we have heard from this particular creditor. We are being sued by the original creditor not a collections agency. As far as we know they do/did have our correct address. In fact when you google my husbands name it's pretty easy to find. Can we claim improper service or that the agency sueing us purposely sent the summons to an incorrect address to receive judgement? Had we been contacted by this creditor we probably would have been willing to try to work out a repayment plan before even contacting a lawyer concerning bankrupcty. We're not trying to get out of paying our bills. Also I believe that this company continously harrassed my father in law who would not give them any info because THEY would not properly identify themselves. And ideas or help would be greatly appreciated. We are going to the court house this week to answer the summons.

Thank you