Maybe I'm being old fashioned but these muppets in the stores need to wake up and smell the coffee!
FACT - Their employers, not their mates etc, are the ones who pay their wages. If they lost their jobs their little tips would dry up just a quickly. They can't have it both ways.
FACT - It makes good business sense to promote those customers who buy from the stores, not necessarily tilers who happen to be mates of the store staff. A good store manager should have a policy in hand to deal with this and be able to pass on the names of a few tilers in the area where the customer lives, not tilers who live 90 odd miles away. If my staff were putting their own interests above that of my business, they would face disciplinary action, with the possibility of losing their jobs.
FACT - If a tiler who does business with a tile shop is being passed over for the staffs' friends then this can be easily tested out with a bit of homework.
1) Do as Neale did and get someone else to go and ask for recommendations.
2) If you don't get recommended, get your friend to follow up some of these guys and find out what relationship they have with the shop. If it turns out that they are mates of so and so who work in the shop etc and don't do much business with them then shop the store muppet to his boss. It's as simple as that!
3) Send people in on a regular basis to ask for recommendations. You will get a sense of how your customer loyalty is being repaid. If it isn't, the manager gets 2 warnings then your business is pulled, along with a letter to head office explaining why.
Cat firmly amongst pigeons!