Don't worry about it.
I had the same, got it all cleaned, customer said I hadn't left a slip. Bugger! I gave them my bank details on a text.
Then they said I hadn't cleaned the bird strike, properly, off their french doors!
So I went back and checked, all looked ok! So I phoned them (thought what's going on)!
I cleaned the wrong house!
What a laugh! 
I had a new customer to start today. Confirmed over the phone after quoting her over a back garden fence whilst doing a neighbours last month. Went to start today at the front and got the houses mixed up due to them being mid terrace. I didn't realise what I had done till after I'd done a deep clean of really minging UPVC frames which came up real nice. When I knocked to get the gate opened, the lady said she hadn't booked me but was so happy with the clean she wanted the backs done and also booked for regular cleans.
In response to the OP I had a customer last week complain that I hadn't cleaned a window because she didn't see me do it. She had been standing right in view when I'd cleaned it but was facing the other way talking on the phone. When I told her she had to concede she'd been mistaken. I just wish people would think to check their windows before complaining, they might save themselves some embarrassment.