Utterly disappointed and disgusted

If i could give Montego zero stars i would,we bought Montego Classic adult food for our daschund about a month ago to help her gain weight after using a lower quality brand,everything went well and about 5 days ago she started scratching incessantly,took her to the vet today and found out that due to the low quality ingredients in Montego she has developed allergies to grain and will most likely have to be on single grain feed for the rest of her life,one would think that a brand such as Montego,classified as one of the best in SA would be reliable but i am utterly disappointed and would advise anyone against buying any Montego products if this is the result.