Hi

I'm flying from WAW to EWR by British Airways and Virgin Atlantic. I'd like to change both of my dates: departure and return. I checked my fare conditions and the cost of modyfing the reservation is 150 EUR + additional fees if the reservation class of another date's flight is higher. However, I bought these tickets via a pretty bad agent and he couldn't tell me whether this cost (150EUR) for modyfing reservation would be applied to both of the dates change, or only one? For example, if I changed both dates, would I be charged only one reservation change fee (150EUR + class differences), or with two (300EUR+)?