However, there has been confusion over the withdrawal of the coins, with some shops pledging to continue accepting the pounds coins after the October 15 deadline.
Martin Kearsley, banking services director at Post Office said: "We would like to reassure anyone who is unclear on what to do with their old £1 coins that the Post Office is here for you".
Poundland also confirmed it will continue to welcome the old coins in more than 850 of its United Kingdom stores until October 31.
With less than a week to go, about 500 million are still in circulation.
The firm will allow customers to pay with the old-style coins for a week after the October 15 deadline imposed by the Royal Mint.
The Royal Mint has advised all businesses should have changed their machines and coin-handling equipment by the end of the week so that they are able to accept the new £1 coins.
The new coin was introduced in March.
He said: "The hard work of the British public has paid off and I am delighted that more than 1.2 billion round pound coins have been returned".
According to data, around one in every 30 round pound coins is a dud with the new £1 coin boasting new security features. These coins and notes are worth up to £37,000!
The coin also has a new design on its tail side, created by 15-year-old David Pearce, who won a competition organised by the Treasury. The Royal Mint has produced more than two billion round pound coins since that time.
It was also warned that continuing to accept the old £1 coins leaves businesses at risk of accepting counterfeits.
While banks and Post Offices will continue to accept your old pound coins, money saving expert-type Martin Lewis explains: "Carting a bag of coins to the bank is a real faff - particularly if there isn't a branch near you".
It may seem like all hope is lost for the round pounds, but don't despair just yet, your options will not be exhausted come the October 15 deadline.
Several charities will be collecting the coins to raise funds.
RBS/NatWest said it would encourage customers to try to hand in their old coins as soon as possible.