Business owners affected by the closure of the Dauntsey Lock Bridge petitioned a senior member of the House of Lords on issue of compensation.
The bridge was shut by Network Rail on May 8, for work to provide an electric rail service from London Paddington to Bristol by 2016.
Businesses in Dauntsey and Lyneham say they have seen a drop in trade, with customers unwilling to use a detour of more than 20 miles.
Lord Newby, the Govern-ment’s Deputy Chief Whip, heard people’s concerns at a meeting at the Pound Farm Shop, Lyneham, on Saturday.
It was organised by Dr Brian Mathew, the Liberal Democrat parliamentary candidate for North Wiltshire, who hopes to build up a compensation case.
Dr Mathew, an aid worker from Yatton Keynell, said: “People brought with them some documents to show how the businesses were suffering.
“There is a duty of care to ensure that companies, especially small companies, don’t suffer unduly because of a project that’s going to benefit people across the south of England.
“What he has agreed to do is take these documents with him and try and build a case.”
Lord Newby heard from Tim Webb at the farm shop, as well as Martin Baker, who has run the Swindon Road Garage for 26 years.
Mr Baker said: “There used to be thousands of cars going past this road and the loss of these possible buyers is devastating.
“The month, before the road shut, we sold 13 motors, but when the road shut we didn’t sell another for three weeks.
“For the first time in 26 years I don’t think we will have any VAT to pay this quarter, it’s been so bad.
“I have spoken to Network Rail, I have sent a claims form in, but they just sent it back, saying they had done everything by the book.”
Tom Laphan, who owns the Dauntsey car boot sale field, said: “Customers are finding it very difficult to get to us because of the diversion.”
A Network Rail spokesman said: “Wherever possible, we will engage with local businesses and look at options to mitigate the impact of our planned work.
“We have two days of visits planned with local businesses in mid-June, to understand individual concerns and see if we are able to mitigate and minimise the disruption as far as is reasonably practicable, for example by offering additional advertising.”
Network Rail will hold drop-in sessions for people to voice concerns. The dates have yet to be announced.