I guess it depends how much you use the remote. That does seem a short life.
We’re still using the original batteries that came with the remote in October. Moderate/frequent use including fast forward of adverts in recordings etc.
Where did you buy the Duracells? Reputable shop? Fresh and in date?
Try another brand. Any good make of Alkaline should be fine. Don’t use Carbon Zinc type.
Nowadays I usually buy from Amazon’s own brand, GP etc. from Toolstation/Screwfix, Aldi/Lidl. Some shops including supermarkets can be expensive.
If it persists ring Virgin and request a replacement as faulty.
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I know a bit about Wi-Fi, Telecoms, and TV as I used to do it for a living but I'm not perfect so don't beat me up... If you make things you make mistakes!