We are 2 UK citizens (British passport holders) living in Turkey who wanted to collect our visa for Iran in Istanbul. We found www.uppersia.com on the internet and asked them to be the ones to make the application on our behalf. They were great - fast, friendly and informative. The whole process took 5 working days. In Istanbul we were careful to arrive at the consulate at 08:30. We were in, completed the form and out to make the bank payment by 09:30. The bank that accepts the visa fee is directly opposite the consulate. The fee was 95Euro per person. By 10:00 they had accepted all of our paperwork and had also agreed we could collect the visa that day at lunchtime (13:00), as we did not live in Istanbul and couldn't easily return to the consulate. This all went like clockwork. We are now really looking forward to our trip.
For Iran visa you can fill in the visa form on Iran visa application , it takes about 3-7 working days to get your reference number and two working days to collect your visa at the embassy by direct referral or one working week by posting the docs to the embassy. You can pay the visa fee in cash in Iran.