Lip filler (Belotero balance) given a weird moustache effect from front! Any advice appreciated! (photos)

Looking at your photos, the moustache effect is from the volume on the upper lip, the biggest is your upper lip then the edge of it goes up and creates a shadow that shows like a moustache. More filler will make the problem worst. You need to get hyaluronidase to get rid of some of the filler to eliminate that shadow.

It's difficult to see from photos whether this is a shadow due to the over filled lips or pigmentation.Beletero balance is not a very bulky filler and it's difficult to see how you have got so much projection using this I would get the whole lot dissolved by an expert and start again carefully. Pigmentation is a different issue and requires expert advice

Your lips are beautiful, but you need just a bit more just above the area of fill in order to decrease the ramped look that has occurred.  The filler is injected into the depest part of the angle to soften the transition between the upper lip skin, and the proper red portion of the lip.