Is my mother responsible for paying heloc my father got. My father passed away. My mother never knew about heloc.

My father passed away May 2016. Later we discovered my father took out a home equity line of credit. My mother never knew about it and did not sign anything. Wells Fargo refuses to show us the original application. We gave power of attorney to a lawyer who got oral confirmation that my mother did not sign anything. Our lawyer says we should stop paying each month. He said Wells Fargo will probably not give back the money my mother paid since my father passed. Couldn't we sue the bank for that. I feel my lawyer is not strong enough to go against the bank. If we do stop paying will the bank try to foreclose. I think the loan is illegal from the beginning because there was no consent from my mother. The bank should not of issued the loan. We paid the lawyer 650 already and he wants to know if we want to stop here and just stop paying the loan or continue and see if he can speak to the higher up people.