Cat need Operasion because of cat food

On the 4th of September I saw my Cat Struggle to Urinate, the 5th of September 2015, I took my Cat to the vet, I had to leave my cat in the Hospital, the Vet said, its because off the cat food. He have a Blocked Urinary track, and Christals. I Use this Cat food for the last 6 months, I use the Royal canin 12 year. I realy am not happy to hear thos Tipe of things, my First bill is R2500, and this is only for the firts day in Hospital. He need to stay there until the 7th of Sep'15. I thought this is a good cat food. I will take this case further. Sorry my Animals is like my Children, and I can not allow something like this to hapen to anyone els Animals.