FWIW, every time (about 6 times in 3 years I think) I've complained about slow connections to my ISP, with documentation from speedtest.net that I'm getting less bandwidth than promised, they've given me that month free of charge.
Yeah, I thought about it, but we recently got the decent-speed option included almost-free with our cable TV (15 mbps for $4/month), so I couldn't be bothered anymore. Used to be on 30 mbps for $40/month.