I have used 2 mesalasine enemas in the past, Asacol in about 2010, and Salofalk very recently.
Both times I noticed no improvement in my symptoms, and in the case of the Salofalk, I did wonder if it was making me worse.
But I will admit that I don't like taking enemas, and get stressed about it. Stress is my biggest trigger for UC. Also by the time I take enemas, I am already ill, so it could be working a bit, just not managing to control it completely, it's hard to tell.
Personally if I was you, I would continue taking them, as prescribed, and talk to your doctor about it. They might have some more ideas for you and you could discuss further treatment options.
I've just noticed in your signature that you are taking Mezavant. I tried Mezavant as a maintenance drug in about 2009, when I was in remission. It made me very ill, I was going to the toilet a lot, and I constantly felt as if I needed the toilet even when I had just been. I went back onto Asacol and was much better. Maybe the Mezavant isn't right for you either?
Before I started taking Mezavant I was going to the bathroom 25-30 times a day, now on a very bad day I go ten, recently I've been going 7 or 8 and most usually 4 or 5