i think barrys post must be a joke because thats one thing you dont do is undercut intentionaly .and you haven,t taken over the cleaning in the area you will look a fool if you say that cause in time their window cleaner will return thats when trouble starts ,just be honest with the custys and if you impress them then you will get the job,if their window cleaner is crap then he deserves to lose them ,good luck with door knocking &keep at it