I've just had a similar problem, though to a lesser extent. I asked to change ether to SNT and was TOLD 329. I was only sent 316.7. Even accounting for their 0.5% 'charge', I'm out by about 13 SNT. I told them about this, and they told me I had accepted their rate of 318, which is LIES. They claim they have a record of this, which is nonsense - I remember what it said before AND I took a screenshot after to check the rate hadn't changed, and they were both 329. They simply deny it, telling me I accepted their rate of 318, which I most certainly did not - why would I, after being told it was 329?!