Reviews of R & T Auctions in Niagara Falls

I recently had R&T auction list several items in their auction like paper money, coins, comics (some signed, some graded) thousands of stamps, sports cards, antique items etc. I was told that if I sold between $5 - 500 there is a 30% commission and if I sold $501 and up there would be a 20% commission. This was also stipulated in a contract. So I thought 20% sounds reasonable. So I agreed. After the auction I find out that they are taking 28% commision for the coins and 30% for the rest of the items. I immediately wrote to the company and their response was that its 20% for each individual item you sell. This is deceitful. Even though i wasn't told that at the time.