Having worked for an EA, the lady had her property on the books for six months, and in this time, especially in the first few weeks, the EA will have run up costs such as man hours spent doing the photo's and measurements for the brochure, printing costs for brochure, postage, advertising costs in the local paper,cost of placing property on websites such as Rightmove, telephone costs, more man hours/petrol doing viewings. So I think that £300 quid is fair. Not that I am sticking up for EA's, in my opinion they are robbers in suits, but wanted to put forward a different slant.
Incidentally, in Suffolk they charge you up front for the brochures, so you have to stump up £295 before they will even market your property, that plus the cost of a HIP (thank goodness they are no more!!), was a fair old sum to find up front.