This is probably going to get downvoted but I dont care. While I agree they are irritating and probably lying, you adding 'lol' to everything you say makes you look very rude. It sounds like you're doing this somewhat professionally, as you mention a shop. Not very professional way of speaking to people. Be polite, and just end the conversation if you think they're wasting your time, dont make things worse by laughing at their questions, which you did before they started to attempt a grift, actually.