Bobshop's Unecthical behaviour

I bought a battery tester for R292.91 from Bobshop, my payment was accepted and the purchase was confirmed. The next day I received a couple of emails confirming a refund to my account and then also a mail in which they claimed that their supplier could no longer supply same….guess what, next day the same tester advertised it for R557. It so obvious what happened in that the amount they charged me and which I paid (R292.91 for tester and shipping)was obviously incorrectly advertised by them and then when they realised it, they unilaterally cancelled the deal and refunded me. This clearly demonstates that their business ethics is highly doubtful and I for one will never buy anything from Bobshop and other potential customers need to know about this practice.