urine problem

Hi my grand father is 93 years old he is having urine problem, like he canot go for urine. so we took to urologist. He put a pipe in his pennis and removed all the urine and he suggested he need a surgery on his prostrate cause it's grown big. A week ago he has done surgery on his prostrate, afer 5 days he removed the tube from his pennis so he can go for urine normally, but unfortuanally he canot go for urine again, that doctor saying he has to do the surgery again. we don't know what we have to do,and we are not understanding what is the cause of the problem, can u suggest me on this case what's goinon.