I had a question regarding fasting. I live in a town with no shias and only one sunni mosque and they have announced that the first of the month of Ramadan according to Saudi is on Saturday April 2nd. We are compelled to fast with the mosque/community. However, my Marja Sayed Sistani has announced the beginning of the month to be on Sunday April 3rd. What should I do?

Why are you compelled to fast? If you kept fast on Saturday it is fine as a Mustahab niyyat