Patek Philippe

I have recently acquired a 1960's 18 karrot white gold Calatrava model no 3537. I have had it serviced and as such, have had it's authenticity verified and confirmed the serial number from inside the case. However, on the face of the watch it says Patek P...  

then I'm JEAN LUC PICARD

Hi. please forgive my ignorance, but why do you think this is not Patek. The only problem I see is that it has GENEVE=GINEBRA (in Spanish) written on the dial. I do not have bibliography to check whether this is a real Patek, but it does seem a well-finis... 

I have the serial number and model number should i contact Patek to find out more ? Cheers