It's OK if they're unable to cope and turn us down right away.
But it's NOT OK to turn down a request for a "final" clarification on a revised quotation that we spent 4-5 sessions of a couple of hours each! It's a complete waste of our time!
We actually sensed that this ID had problems managing his time and was very slow in his quotation, so we asked if he could get someone else to handle our project. But he continued to assure us that he was able to cope... hence we spent a few more sessions with him and arranged a site visit, only to have all out time and effort wasted!
BTW, we actually send an email to the bosses of the company. Guess what, we received not a single reply. So it says so much about the company. Yes, like many other renovation companies, this company has hired many ID/sales to boost their sales volume at the expense of quality.