Gelderd is one of three Labour MPs calling for a rethink and said constituents told her “this is critical” for them.
The proposal came seven months after toll fees went up to plug a hole in finances.
The committee said it proposed the changes as it needed to maintain a “prudent reserve” of £3m.
Campaigners said the crossing was crucial for people who cross the river for work, education and appointments at Derriford Hospital in Plymouth.
The committee told the MPs it rejected other options including reducing the TSG discount, increasing the toll or reducing the number of ferries or toll booths.
