Home Information Pack providers collect together the necessary information and produce Home Information Packs (HIPs). If a HIP provider is not an estate agent, then the handling of a complaint depends on whether they subscribe to an industry code of standards such as the HIP Code.
If your HIP provider is a member of the Association of Home Information Pack Providers (AHIPP), they must subscribe to the Code.
There are other bodies, like the Independent Pack Providers Association (IPPA), whose members provide HIPs.
If the firm does not subscribe to a code of standards then there may be no formal process in place to help you. You should contact Consumer Direct for advice on how to get legal help.