Guild Wars 2

Just a question to all and any willing to answer.
I was off Gw2 for a total of 5 days, and had 700gems.
When i logged back on i had 100gems.
I have nothing showing in my recent purchase history and i know i only converted 200gems into gold.
Has this happened to anyone else?
or should i just accept the fact that i some how lost 400 gems?

Yeah, if this could be done, i would be most grateful xD
I have a set of armour just sitting in my bank waiting for this hopeful feature to be included :P