Fishaways cheated me with my order

I normally buy from Fishaways at Blue Valley Mall. Today i ordered 2 F2's Medium fish and chips. When i got home i realised one fish was Medium but definately the other one was regular. I know the sizes well cause i buy it often and you could see when you put them next to each other the other one was very small. Its very bad to but take away and the shop takes advantage that you wont open until you get home and rob you of your money. Very dissappointed.