Unbelievable price difference

So, I usually shop at Checkers, and occasionally at Spar. We buy Whiskas pouches for our cat. Spar price is consistent - R89, Checkers - R96.99! I did a shop at Checkers today, thinking I'd buy the cat food since the extra distance would've anyway cost me more, guess what? Checkers are now charging R105.99!!! I refuse to pay so much more :( What is the huge price difference about Checkers? Spar are a much smaller shop, I would have thought Checkers would be cheaper, very, very disappointed