Grades through clearing entered wrong

While I was entering my grades through a university's clearing website, I somehow managed to enter the wrong grades for Physics and Further Maths, I got an E for Physics and D for Further Maths but I entered the opposite grades for the 2 subjects on the clearing admissions. I managed to get an offer from the university but I'm worried that now that I have sent a confirmation of my actual grades I will be rejected from the university. I am planning to call the university as soon as it is open tomorrow but I just really need to know if I should expect to be rejected.