Sell it la. Should really stop communicating with them. His brother only knows him when they need the instalment. Don't use money to buy family relationship. Should really punish them, let them know your bottom line.
If I were you, i would even stop picking up their calls. No chance for them to 乞. and now it is only the brother to ask for help, how about his wife? even not saying a sorry. 乞都冇誠意