While that "hold" does seem high, it happens with many companies. I bought less than $20 worth of gas here at home yesterday and the place I bought it put a "hold" or pre-authorization of $100 on my card. Another gas purchase at a different station resulted in only a $1 "hold".

This has been discussed before and I forget if it is actually the merchant placing the "hold" or if it is the bank the merchant or card uses. I know one station around here has sign posted on their pumps that address this but I don't recall exactly what they say.

You might try calling your credit card and running this by them and/or asking for a credit increase to offset this.