Thank you for your question. There can be several reasons why your filler failed you in the NL lines. You may degrade the filler substance quickly, the injections may have been too deep or not enough, etc. It is difficult to know what the underlying problem is. There are other fillers that are made of different substances and produced in different ways (more cross-linking to prevent quick degradation, for example). You may want to try another injector. Finally, structural fat grafting is a nice way to "plump" these areas--it is your own fat that is used and transferred to the NL folds, that adds volume and is essentially permanent. Best of luck.
Pictures would be very helpful to give you the best advice. Is the issue with your nasalabial area really only a line, or is there a fold as well? If it is only a line, sometimes fillers don't work well because the filler is injected too deeply to affect the line. Injections to treat a line must be injected superficially to have any effect. A filler called Belotero works well for this issue, since it can be injected superficially. Some of the other fillers need to be injected more deeply, so they would not be useful to treat a line. If you actually have a fold, it's possible that the filler could be placed into an adjacent location to improve the fold, without placing any of the filler under the fold at all. Without pictures, I can't tell what your best option might be. In general, Botox would not work well on nasolabial lines.