Thank you everyone, for all your suggestions. I did send a letter to the Manager, stating amongst other things, that I will take the matter "further", and that I expect to have my money refunded. Then yesterday I got a phone call from the sales assistant telling me that I can come in to get my $50 refund. I don't know what made the Manager change his mind - I'm just glad to get my money back. (Perhaps he saw these posts on the newsgroup?)
In any case, even though I got a refund, it doesn't change the fact that the manager was rude. I would still not recommend purchasing goods from Statewide Sewing mainly because of their aggressive attitude.
I have made a note of all your suggestions, so that if this ever again happens to me or anyone I know, I will be able to give them your ideas.