Bravecto fails to work

In December 2014 I was sold a product to get rid of and prevent ticks from getting onto my 3 dogs. I normally use front line but the Consultant told me that Bravecto is the best and works a 100%. I tried it on my dogs and it did not work. It did not get rid off or prevent ticks from getting onto them. I went back to the vetshop and they referred me to the Supplier. I sent the supplier an email and received a displeasing response from Dr Chel*****sey. Firstly she stated it worked on her dogs, then she stated that it works in a way that did not make sense to me and stated that the consultant wasn't trained to sell the product. At the end of the day this product was expensive and not work at all. It was tried and tested on my dogs. No excuses, a refund should have been given if a product does not work. I have email correspondence to back up this complaint.