I was totally sold on your service and your product until I opened my last order to discover that you'd sent the wrong size cartridge. I returned all cartridges including the open one but your operative refused to replace the one I had opened. I thought this was poor - being prepared to sacrifice my long term custom for the sake of one lousy cartridge. But your operative would not budge, forcing me to look elsewhere. I would have rated you 5* had it not been for this. If you offer to replace the opened cartridge, I will consider giving you my business again.