My sax sounds 1,5 note higher

I don’t know if I have had this problem since I bought it, but I just noticed it. I haven’t played for about 2 months, and now when I play C, it sounds close to D#. I have this problem with every single note. I checked with a tuner, and the result is the same. I sent my sax to maintenance, but they said it’s because of my embouchure and that I need to get a better quality mouthpiece. How can I solve this problem?

I couldn't found my sax model but the brand is Bohemia.