Hi @Samito the Charge is an all in one device and the band can't be changed. Sure you have a Charge? It's been retired for a few years and no longer being made. Let us know which Fitbit you have.
If recently purchased, it should be a Charge 3. Is tour band removable. If so then bands can be purchased at the Fitbit store, Amazon, and some local brick and mortar stores like Best Buy and Target. I've seen them in other places.
Now if it is a 3 year old Charge with a glued on band, Amazon has replacement kits,
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