In the event that the revenue from fees calculated for the benefit of communes, public establishments for inter-communal cooperation or mixed syndicates pursuant to articles R. 2333-105 to R. 2333-108 is lower than that resulting from the application of the specifications in force, the fees shall continue to be established in accordance with these specifications, unless an agreement is reached between the communes, the public establishments for inter-communal cooperation concerned or the mixed syndicates and their concessionaires.