We will not seal a bat colony in the maternity season
From roughly June to late August the young cannot fly. Sealing the entry traps them inside the wall, and several of the species that roost in attics here are protected in Ontario.
What we will do is survey it, find where they are getting in, and book the exclusion for the first date it is both legal and sensible. Anyone offering to seal it in July is either uninformed or counting on you being. The smell afterwards is what you would remember about the cheaper quote.