Botox not working
I am going to guess that you went to a "medspa" and not to an office of a board certified dermatologist, facial plastic or general plastic surgeon for treatment. If my guess is correct then you have your answer as to why you may not be achieving your goal. You don't pay for the syringe, you pay for who is holding the syringe.
Botox losing effect
Although it sounds like you might have too low of a dose, when you have had 3 consecutive treatments in a 7 week period, I would be surprised. it is possible you are developing a resistance to Botox. I would discuss this with the practitioner who gave you the treatment - they will be able to see if an alternative neurotoxin may be able to give you an improved effect.
In most cases, in the USA, when I see lack of Botox response, it is usually due to poor injection technique by an inexperienced injector, over dilution of the Botox, or underdosing. I recommend that you see an experienced injector. It is rare to have a resistance to Botox. You can try Xeomin, referred to as "naked Botox". It may work in someone who is resistant to Botox Cosmetic. Your best bet though is too see a reputable injector with considerable experience.
Not getting same results from Botox
It is possible that you are developing some antibodies to the Botox. I don't bother checking for these, I just try using Xeomin, which is a "naked" toxin to which you don't develop antibodies to. As stated in other docs answers, it's possible the Botox is old, dilute, or not properly injected. It is also possible that what is being injected is not Botox at all, and either counterfeit or something else. Stick to a reputable doctor for this.
I agree with Dr Elson, the common reasons for no response and poorly stored botox (too warm), old botox typically older than 2 weeks after hydration, under dosing which is common in smaller practices, poor location and finally and rarely biological non repsonse. I have seen biological non response however and it can be addressed in my experience by changing from botox to dysport. If you trust your practitioner then ask them to try dysport instead. That may well do the trick
Botox not working
There are a number of reasons that you might not respond to Botox. It is possible you have become a non-responder although this is very unlikely as it does not occur very often. More likely you are either getting injected by someone not experienced, the Botox is diluted too much, the Botox is old. the main thing is to be sure you are getting injected by a board certified or equivalent dermatologist or plastic surgeon not someone in a "medspa"
Botox not working
Hello. I'm so sorry to hear about your problems. This is a common problem in the UK because of lack of regulations on who administers Botox and a lack of knowledge of products. Stick to a reputable clinic who show you the product injected, expiry date and have Doctor with good experience to inject. I have seen a few cases of resistance to certain brands and the solution is normally to switch. Seek an expert it is always worth it!
In my experience, Botox results are dependent on the person who does the injections. I would recommend that you choose a physician who has experience and a reputation for performing well. I would work with this physician and allow them to identify a treatment regimen that works for you. This may take several visits but you will likely be much more successful this way. Best wishes!
Botox isn't working
Usually when I see patients who have issues with Botox not "working" it is because of insufficient dosing. I'm unsure why you are going to two different clinics but that could be inhibiting it more actually. Without one knowing what the other is doing it is really hard to treat you effectively and consistently. Find one office that you like that does a good job and stick with it. Botox should not be purchased on price alone - there is a big art to injecting and dosing properly.
"This answer has been solicited without seeing this patient and cannot
be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."
Botox not working as well as previously
It is very rare, although possible, for patients to develop "resistance" to botox. However, most commonly, when this happens, it is related to insufficient dosages or placement. There seems to be some effect in the photographs, so likely an increased dosage may be needed.