It sounds as though you are having bladder spasms. The bladder is irritated by the catheter and balloon and it will push urine around the ballooon. This is called catheter bypassing. I would try a smaller catheter - a 14 French. Or you can try medications called antimuscarinics or overactive bladder medications. They include a skin patch called Oxytrol, and 5 pills called Detrol LA, Ditropan XL, Sanctura, Vesicare and Enablex. Sometimes these medications will calm down the bladder so it will not spasm. The best solution is to remove the catheter but you may not be able to do that.