I never had a customer who paid more than 3% for a purchase. I also don't recall any Turkish vendor not paying 3%. If they had a problem with that they would nearly always work it out in their head..."£60,000...if they sell it I'll have to pay them...£1800...ok, put it up for £62,000". That's the case, and never once did they say to me "charge the buyer all 6%".
Where it all goes dodgy is where the seller has told the agent he can take his 3% out of the sale balance, then the agent tells the buyer they have to pay 6% because the seller won't pay. 9% commission on a 62k apartment for example - nice work if you can get it.