Small businesses in Streatham are being hit hard by post office strikes that have left three million letters undelivered across south London.
Cheques and invoices sent through the post have been undelivered or delayed, badly affecting businesses financially.
Small business representatives have warned if postal strikes continue, businesses will struggle to pay rent or will start breaching contracts.
The post backlog has been caused by a series of one-day postal strikes by members of the Communication Workers Union against a new delivery system.
Businesses already badly affected in Streatham include Dowsett and Jenkins funeral directors in Sunnyhill Road.
Staff have had to hand deliver invoices and important funeral information to mourners planning loved ones’ funerals.
Jacksons estate agents in Streatham High Road has suffered problems from delayed delivery of contracts which is complicated people buying, selling and renting homes.
Roland Boakye, owner of the month-old Fizz DJ and Music Store in Leigham Hall Parade said he faced a £100 fine for filing his first VAT return late, because a letter to him from the Inland Revenue was delayed by two weeks.
Stephen Alambritis, chief spokesman for the Federation of Small Businesses (FSB) said: "Our research suggests 70 per cent of small businesses rely on the mail to send cheques and receive income.
"The key concern is that cheques aren't being banked and businesses are starting to incur extra charges.
"This has huge ramifications. If the situation continues, businesses will struggle to pay rent or will start breaching contracts.”
But Ray Hall, head of the Crystal Palace Chamber of Commerce, suggested the impact of the postal strike on businesses could not be as bad as feared.
He said: “Many businesses use the internet to make payments and take orders so will not be affected.”
Further strikes are planned for Wednesday, September 23, and Tuesday, September 29, but negotiations have been taking place between Royal Mail and the CWU to try and resolve the dispute.
Postal workers are objecting to the new Pegasus delivery system, which calculates delivery routes for post workers.
Royal Mail has said it will make services more efficient while the CWU have said it will lead to redundancies, and postmen working longer rounds.
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