Tombco Tombstone? Thank you next!

I had recently went to Tombco store in Welkom and entered into a lay-by agreement. So when I was halfway done with my payment I saw a better deal in their new brochure, when I approached them to cancel my lay-by agreement they told me I can't so because I had seen the posters in their offices that stated "no refunds on lay-by" goods but once they saw that I knew my rights as a consumer only then did they allow me to cancel my lay-by but after much arguments.. So really it's not a good store because they rip people off who are not aware of their consumer protection rights. Also they don't include delivery and installation on their deals but they don't make people aware when entering into the deal they only let it be known once you've entered into the agreement.