1• I cannot agree with • I don’t share your point of view on this.• I cannot accept. • I disagree with…
2• I don’t see it that way. • I think otherwise • I am not sure about that • I don't think so
3• You are quite wrong when …
4• I am sorry but I don’t share this point of view. • I am afraid I can’t agree with you.
5• I don’t believe it to be true that… • If this were true…
6• You are wrong • I totaly disagree • Absolutely not! • That's not right
Note: 1-2-3 and 4 are more polite ways to express your disagreement, but 5 and 6 are less polite ways and more brutal or frustrating indeed.