Blatant overcharging for books purchased

I bought 3 e-books on-line over the weekend. Listed prices on Kobo webpage were: R121.24, R145.59 and R113.39. I was invoiced R138.21, R165.97 and R129.26 instead - and then VAT was added on top of this! The first prices STILL appear their website. A 20% discount voucher that I redeemed was also not honoured. This is not the first problem I have encountered with Kobo. Please be aware of their ********* business practices and rather buy an e-reader from the opposition.