Why don't you do a special promotion?
Use vista-print (or someone else) who do the "Free" special offer for the valued customer (every week)
I got the large Post Cards (I think it was 250 for the price of 50...about £5 delivered)
I placed one in every customers bill.
The offer was £5 off next clean(or 25% of new clean price, which ever was larger.. for each and everyone!)...
When they recommend a friend/family member/neighbour etc! (condition was "Regular" customer! at least 3 months)
One customer went out looking for people she knew, so it worked for me!
