I wanted to obtain a 30 days visa through the Iran embassy in Paris, France.
I contacted Touran Zamin, a travel tour operator in Tehran, online and asked for their advice. They answered promptly saying that for 30 days an authorization number was needed, which they could obtain for me for a fee. I filled up the form online, paid the fee online as well (35Euros + bank charges) and got my authorization number, which I brought to the Embassy together with my filled in form for a 30 days visa.
When I went to collect my passport + visa I discovered that it was only for 15 days. I tried to argue with the clerk, without success...
I then contacted Touran Zamin again online to ask for their assistance. They responded saying that "this happens sometimes, but do not panic, visa can be extended in large cities in Iran"! They also added that they had correctly filled in the demand in my name, hence they had fulfiled their duty. Followed a tense conversation on Skype during which they finally agreed to try and fix things with the FA ministry in Tehran.
I finally had to go again to the embassy in Paris and got my visa corrected to 30 days in extremis, on the day of my departure!
Just wanted to warn you people...