Same thing I would do with most places I am not happy with the service at. Take my money somewhere else, and advise those I know who go there to do the same.
Ive worked in retail before. If nothing else is hammered in to staff, its that unhappy customers go elsewhere, and generally take other customers with them.
If you have a good track record with them, it may be just a one off.
- Not a site sponsor :D