I've flown to Istanbul a few times this year on business (out of LHR). I'm not sure about the fare codes, but the 'Economy Promotional' fares as listed on the THY website (the cheapest) will earn you 0 aeroplan miles, mimicking the pattern of other Star carriers in Europe where the absolute cheapest special fares are ineligible (see Lufthansa and Austrian). But, you should get the full 100% for any fare basis higher than that including the 'Economy Restricted' second lowest fares. Consider Economy Promotional as Tango and Economy Restricted as Tango Plus... the price differential is similar to the differential between Tango and Tango Plus on AC too.