When I took Vesicare, it was once a day. I started out with 5mg, which wasn't working, so my doctor had me double to 10mg, but still taken at the same time. I always took them at night to lessen the side effects.
Not sure what other OAB meds you have tried but there are several. If Vesicare is not working, ask your doctor for something else. If your doctor is unresponsive, find another.
Botox works best for me. Hope this helps.