Barry Davies, his wife and their friend, who uses a wheelchair, went to the public toilet block near the swimming pool off the A529 in December.
The town council's toilet block was in the process of being refurbished and the lock had been changed, so Mr Davies' friend (who did not wish to be named) could not use her national Radar key to use the disabled toilet as normal.
"We had used these toilets before," Mr Davies said.
"But after a few minutes she said 'I can't get in'. I looked at the door and it's a brand new lock.
"They have closed the men's and the women's, they're going to make it into a unisex block.
"My friend soiled herself, she was very embarrassed about it."
He said that there was no sign explaining the change in the system. The refurbished unisex block was due to reopen on Monday this week but it was delayed until tomorrow.
Councillor Roy Aldcroft said that the Radar key lock was removed so that everyone, including disabled people, can use the new unisex block, which will be open from 8am to 6pm.
He said that what happened to Mr Davies' friend was "regrettable" and conceded that there should have been signs explaining the issue.
He said: "That is unfortunate and regrettable.
"He is quite right, what we hadn't done was put signs up saying they were under refurbishment.
"There were signs saying the toilets were closed but there wasn't one about refurbishment.
"It was unfortunate but the disabled toilet at the swimming pool was open."
He said he has apologised personally to Mr Davies though he cannot speak for the council.
But Mr Davies disputes this and said he has not received an apology from anyone connected with the council.
"I'm not disabled, I don't live in Market Drayton, I just think it's wrong," he said.
"It just seems like we're going backwards."
He was also sceptical about the removal of the Radar key lock, which he said was "ridiculous".
"It will be closed more than it's open with vandalism," he added.
"Basically the disabled are being punished as the youths can go inside, lock the door and it's a safe haven, but then when a disabled person wishes to use it it will be full of needles, weed et cetera."