Sure you do. Compete back. Preferably on price and quality of your product rather than the prettiness of your pictures.
Anyone can take a picture of a CPAP machine. Yours aren't special, and if that's what's harming your business, you're doing something wrong. Probably a lot of things.
Anyone can take a picture of a CPAP machine but not every can do so after 5 years experience serving customers using them. What angles do they want to see, what zoom shots make things most clear, how do those zooms relate to the specific features and usage of that machine/mask/product.
CPAP is unfamiliar and visuals are the guide. It is important to do it right and hard to do it right. I think they are special as are the people who made them.
Decent photography has a real-world cost attached to it. Why should the fact that anyone else can do it be a reason I give it away for free, with no attribution?
Presumably there was a cost to figuring out the angles and zooms that showed these machines in the most informative way. Do you think that particular, informed camera setup should be patented?
If not, why should the particular photographs be copyrighted or otherwise excluded from use? Presumably when setting up your business (or the OP's), they looked to other more successful businesses as an example to follow. Should those other businesses be compensated for contributing to the OP's success?
What makes one idea, or expression of an idea, exclusive, private property, while other, often more valuable ideas, are free for the taking?
Sounds to me like the OP is trying to suppress competition through rent seeking, rather than competing on an even playing field by providing more value to the customer.