House almost in foreclosure help?

So my grandparents are like 100 years old and don't really understand a lot of things so I try my best to help them. They have been living in their home since the 70's but they took out the equity in the early 2000's for repairs on the home. between that and other bills they fell behind and ended up filing chapter 13bankruptcy in 2011. They had a 5 year repayment plan which included their house and car and other debts they owed and they made the payments on the house and bankruptcy just fine. Their bankruptcy was finally discharged in February 2016 and since they are older they got cashier checks and sent the mortgage payments to the bank (Wells Fargo) by mail. They received a notice in the mail in July that a different bank took over their mortgage unknowingly because they haven't made payments. With research Wells Fargo cashed the checks but did not apply them toward their bill. We have all the bank statements and copies of the cashier checks that were cashed as proof. They started sending payments to the new company and speaking on their behalf of them I called to see if they received the payments. They said they did not receive anything and they are in the process of foreclosing the house because of lack or payments received. At this point I'm not sure how to how to help them. The company is saying they owe about 4 thousand dollars in missed payments. We have proof of payment should we get a lawyer?