Maybe I am doing something wrong here, as when I go door knocking and as soon as they say they have a window cleaner (after I ask them) I walk away without going into any more depth esc the charges.
I think it maybe still a fine line of undercutting although 2 weeks is far too often and agree with you there but also 2 months is too long.
The way I look at it, is would you like it done to you, i.e, someone going round once a quarter to save them money?