Is there a 'BTC Refund Department'? I have been scammed 6 months ago.
Now someone is calling me from BTC REFUND DEPARTMENT. He said that I have under my name the bitcoins that have been scammed. But the way to take this amount is to synchronise my wallet with the address that the amount is under my name. The issue is that he is asking for 10% of the amount to be added in the wallet and send the new bitcoins to blockchain and then after 15 minutes all the funds will be in my wallet.
Has anyone had a similar experience? Is this true or is just another scammer?
I have been scammed 6 months ago

Then criminals expect you to be gullible and foolish. You are a prime target for them. So they'll try new ways to trick you.

BTC REFUND DEPARTMENT

No such thing.

synchronise my wallet with the address

They want to fool you with a watch-only address, where your wallet shows an amount of money that belongs to someone else not to you. Addresses are not secret. Anyone can add any bitcoin address to their wallet but that doesn't give you any control over money.
Bitcoin wallets do not actually contain money. Wallets contain a secret number called a private-key that a wallet can use to control money. Importing an address doesn't give your wallet this secret number.

the amount is under my name

That's not how bitcoin works.
Some businesses that sell bitcoin might ask buyers to set up a named account but that's outside the real Bitcoin system.

hi is asking 10% of the amount to be added

This is often called &quot;advance fee fraud&quot;. Don't be tricked. There is never a need to pay any fee to release money. If there were, it could just be deducted from the amount being returned, you wouldn't have to pay it first. This is a favourite trick of confidence tricksters.

Is this true or is just another scammer

It's not true. It is just another scam.

See also answers to questions about

watch only addresses
non-spendable addresses
fraud (Bitcoin)
scams (Personal Finance)