Oh, God, save me from these people...HELP

Yes I said it...I'm about to throw this mother and daughter out on their ear. Frankly at first I really didn't notice them but then they came to the counter and the mother, of course, let's the precocious child do all the asking, the problem with that is the kid didn't understand a word I was saying. So I had to keep saying it over and over and I kept looking at the mother (these were American's people) like..Do you want to take over here? but she just kept ignoring me and letting the brat ramble on. And then I noticed it...this kid was covered with sand...first of all let me say growing up I was taught you didn't wear white after Labor Day (and I don't) and you don't appear on the boardwalk in a bathing suit after 5:00 p.m. and I don't. So the fact that it's after 6 p.m. and this kid is standing here in a bathing suit is a problem for me, but the bigger problem is this mother (and I use the term loosely here) brought this brat in here covered with sand...yes covered with sand. That I couldn't let pass so I said to the kid, "My God, what did you do roll around on the beach before coming in?" Idiot that I am I thought the mother (and again I'm using the term loosely) would recognize her faux pas and take the child outside at least and brush all the sand off so it doesn't end up on my floor. Well, that just prompted her to take another walk around and now she's asking the stupid questions. Actually, the first question isn't stupid...she asked where the beachy kind of kits are...but after I said, "They are right there on rack 41..and I'm not only pointing to it by walking behind her (she was too stupid to get out of my way) and she stopped at every rack (well there were only 2) and said is this the rack? Now she asked for kits and clearly the racks she kept stopping to look at were charts only...I mean it doesn't take a mental genius to figure out if its a kit or a chart...well, maybe it does. O.K. so she and the brat just came up with their items only to say, "We didn't bring much money because we didn't know....(she never actually finished the sentence)" so she wanted to know how much 2 of the items were so I rang them up, then she says, "I don't suppose I have enough for this (a $6 Mill Hill kit)..." Now I already told her the 2 books were $13.78 and she brought $18.00 before she then asked if she had enough for the $6 kit. O.K. so in your head you add $13 & $6...and if I am correct that would be $19. Clearly $18 isn't enough, but her brain couldn't do that high math apparently. Even after I told her it would be $20 she stood there fanning out her $18.00 and looking at me like I'd forget the other $2 and just give it to her. Now I'm become a charity for sandy, annoying people...I don't think so. My God, it's Sunday and there is no charity left in my bones today. But today hasn't been all bad...Stasy S. was in with her parents, Carolyn (my finisher..although without stitching lately there hasn't been anything to finish), and Lou, Carolyn's husband. So we had a good time talking and catching up before sand girl hit the shop. But now I'm forced to go sweep the shop to remove all evidence of her, although as she was leaving she asked if I'd hold the other two items and she'd come back tomorrow. Crap, if I had know that I'd have given them to her just to keep her out (well, maybe not). Well, it hasn't been 2 hours and she's back....and now she brought back another woman and a baby, but I am happy to report that the sand girl has changed out of the bathing suit. But the woman is as big an idiot was she was 2 hours ago. She lets the baby knaw on one of the Mill Hill kits all around the shop but doesn't bring it up to pay for it and tells me "I've decided not to get the chicken kit." Yea I guess not now that that kid of yours has slobbered all over it. I'm telling you it's all I could do not to bitch slap her...but I refrained simply because I didn't have the energy. Now I have to replace the 'chicken kit' packaging. Fortunately he didn't get through the bag so the kit is actually safe, just not the outside packaging.