I am worried that the visa rules in general are tightened and the VOA is suspended. Do you think that I should go ahead with my visa petition though a reliable Iranian travel agency with a good track record ASAP!
Iran visa and VOA rules are not going to change, so don't worry about it at all. For the visa to Iran you have three ways:
1. 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.
2. Fly to Iran and get a 30-day on arrival visa at the airport. This kind of visa is issued for 98 nationalities excluding USA, England, Canada, Colombia, Pakistan, Afghanistan, Iraq, Jordan, Bangladesh, and Somalia. If your nationality is among the countries authorized to get it, you can easily collect you visa against offering your passport, a passport-size photo and about 10-150€(depends on the nationality) to the staff at the airport. There is no need to fill in any form beforehand.
3. Refer to the Iranian embassy in your country and ask for a visa to be issued for you. Usually this way takes longer time about 30 days.
This visa is valid for 3 months to enter Iran once being stamped in your passport.