The first error is the architect adding 5 courses to the bregs drawings. The second error is the builder changing the roof specification, which compounded the architects error because it also required them to add more courses to the parapet in order to 'cover' the additional roof height.
Had the roof been built to original specification, and the parapet been built to the architects error, the parapet would now be 5 courses too high. But 2 of those courses could be removed without requiring roof removal. The net result would be 3 courses too high, which you might have been able to negotiate with planners.
Therefore, both parties dropped one but the builder dropped a bigger, more serious one. I make it 80:20 and you might suggest that each contribute that proportion to resolving the issue.
PS, what on earth is going on with the side wall tying in?