We had bad experince with myholidays. We had a honnest tiny mistake when we choose our dates of flight.
When we asked them to help us to correct the dates, they refused to help us, and wanted about 200$ for each ticket for the correction (the oeiginal price of the tickets was 290$ each).
We are really recommened to everyone not to buy their tickets via the site myholidays- they have no will to help their customers.