Angry Shopper SF vs. T-Mobile

My wife and purchased USD$ 50 unlimited SIM cards to use in our iPhones while traveling in San Francisco. However when we tried to use the SIM's in our phone with either got no service or poor reception. The only places we got coverage in SF were either in Crissy Field or down chetnut street. We went back to the Chestnut street store the next day only to be told that the plan were non-refundable and that the sales assistant typically had to stand outside the store to use her t mobile line. Unbelievable - a T Mobile store selling calling plans in a store that doesn't even have T Mobile coverage. This s day light robbery. And what can we do about it? Nothing! We just spent over 100 dollar on nothing. Maybe I'll have to stand outside the store with a placard discouraging potential customers and warning them about potential robbery within the chestnut store. Anyone out there who wants to on in on a T Mobile protest down on chestnut street?