Question about be quiet! Straight Power 11 Platinum

Good morning digitec team I wanted to order this product, be quiet! Straight power 11 (750W) Platinum and for some time ago was 142chf but today cost 196.01chf. Please can you inform me why you change the price of this product? Another product in the same family (be quiet! Straight power 11 (850W) Platinum with more power cost 165chf Also in the web site of the manufacter https://www.bequiet.com/en/powersupply/1768 all these products have 5 year garantie and you give only 36 months, why? Thank you