CLICKS VERSUS DISCHEM PRICES

On 10th September I paid R305.00 at Clicks for a 100 Bottle of SLOWMAG . I have my slip. Yesterday when I was in Dischem Century City they were selling the very same amount and same tabs of 100 Slow Mag tablets for R259.99. Why the huge difference of +- R45.00 at Clicks. I could understand a difference of say R20.00 - but R45.00 is a bit steep! I even took a photo of the Dischem price- so i n future I will be buying all my tablets from Dischem.