Video footage will be sent to the FA as Town bid to overhal Tuesday night's sending off of Andy Williams.
The Welsh winger was given his marching orders by referee Keith Hill after picking up two yellow cards - the second for diving.
However, footage clearly shows that Millwall keeper Tony Warner made contact with the player as he broke through in the 52nd minute.
In near-farcial scenes Williams was shown red and Town boss Colin Todd was banished to the stands after a bust up with officials.
This is not a case of sour grapes on Swindon's part - for once they were truely robbed.
What made it even more galling was that after the game keeper Warner admitted there was contact made.
Richard Sadlier had put the Lions ahead in the first half and added a second late on as Town were caught on a break.
Chief executive Pete Rowe said: "I believe we have a good case to show the FA and I will be recommending that video footage of the incident is sent to the disciplinary baord to get the decision overturned."
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