I am familiar with the enema kit you are using. The enema nozzle and the shut off valve can be replaced. The hose, I believe, is a 7/16" standard hose. You can order a new plastic shut-off valve and and new replacement nozzle.
I do not use a kit but buy each item separately. At present I an using a 4 quart bag, hospital grade, 7/16" standard grade hose, a plastic shut off valve with an adjustable “click” stop to control the flow, a pink bulb head nozzle for better control and retention. I also use a colon tube #24FR close end.
There are many suppliers of enema equipment. I will list a few of them.