What should I do if the procedure looks unnatural?

It seems like many people are choosing Botox or fillers for various reasons. However, I’m curious because procedures don’t always succeed and yield great results, right? What happens if the results don’t turn out the way I wanted after getting Botox or fillers? Is it best to just wait until the effects wear off? Or do people usually opt for additional treatments? It feels a bit wrong to get extra treatment on a place that was already messed up once, but I also don't think it’s right to just leave it in an odd state until the effects, which last for nearly half a year, disappear. I’ve heard that sometimes a place looks fine at first but changes shape over time, so I’m curious how people handle that situation. Is it common practice to return to the clinic where the procedure was performed for a consultation, or are there cases where people get corrections or additional treatments at a different clinic? I’d like to know how those who have actually experienced this situation proceeded.