Retailers are free to refuse any means of payment, even those with legal tender status should they wish to do so. Some businesses, for example, refuse to accept Bank of England £50 notes.
Legal tender status has a narrow technical meaning. If a debtor pays in legal tender the exact amount he/she owes under the terms of a contract (and in accordance with its terms), or pays this amount into court, he/she has good defence in law if he/she is sued for non-payment of the debt.
The Government has no current plans to extend or replace the current legislation relating to legal tender status.