Modifying submitted Renta

[Curiouse]

I have just made a stupid error , a few minutes after submitting my Renta i realized one of the sources of income i didnt not convert to euros , i returned to try to modify it and selected Modification but after changing the amount went to submit again but it wont allow me to . I am concerned as it meant i am underpaying my tax by about 70 euros . Is there any way i can correct my error online . After 10 years of doing our Renta this is the first time i have made such a silly mistake .