Lost space1960

Hi I had bought two tickets that the price was 57,60€ from your travel agency site GetYourGuide for the national museum of Prague in 2 January! When we went to entrance in the museum they stopped us. As they said these tickets are a scam and are not valid. So that we bought a new tickets from the museum which the price was cheaper than your site. 360 czk per person So 360x2=720czk In euro 14,82 per person. 14,82x2=29,64€ Please I would appreciate if you can help us to not lost our money.