The discount codes only work when you buy directly from HomeHealth. If you buy from eBay or Amazon, you will pay the usual £6.99 per tub - unless you buy from a private seller who wants to be rid of some they have acquired and are just getting something back for something the no longer want or need - plus Homehealth will pay a fee to eBay or Amazon to use the sites. I always go directly.
If going direct allows Homehealth to protect their profit margin enough to be able to offer us a discount provided we buy a few at a time, I'm all of that. I like a win/win story.