FNB offers migration at "no charge" but charges anyway

I had a premier account with FNB and out of the blue one of your so called consultant named Peter phoned and offered to migrate me to a fusion account at no additional fee. Thing is that i already paid for the premier account - a fee of R275 on the 2nd of August. I agreed to migrate but then this morning i received a notification that another R170 odd was deducted for my fusion account fees. I phoned and apparently this is "luckily'' only pro-rata for the fusion account...gee thanks FNB!! why cant my pro-rata rate be refunded then for my premier account that was paid for the full month of August? OR why cant you start me on the 2nd of September when i got my full money worth out of the fee i already paid for the premier account? R170 doesn't sound like a lot, but i'm sure FNB does exactly the same with a few hundreds of people. To put it into perspective...if they can "migrate at no additional charge'' for 1000 people, that's almost R170 000 in one month. nice pay day for the person that came up with this ********