Hi Folks,
We have an application with 178 forms.
The client decided to replace all third-party controls with microsoft controls.

So we decided to go with basic controls like command buttons / check boxes / option buttons / frames / date controls etc.

This took about 6 working hours for 1 form. Now this was a fairly large form. So I averaged out to 3 working hours per form for estimation purpose.

Now I estimated that the change will take 178 * 3 = 534 working hours. That translates to roughly 66 person days. I informed the client about it. He says its crazy and tells me that it should be done in 20 days. Though our negotiation has not yet finished, how do I convince him to accept my estimate?

My developers are the ones who are terribly upset and are talking of quitting all the time.