It stated some troops are being failed in areas such as compensation and claiming entitled help.
The charity wants ministers to ensure the deal takes centre stage in policy and is upheld by local authorities, and has asked supporters to sign an open letter to the government on its britishlegion.org.uk website.
It has also found that a quarter of the military population and 67 per cent of civvies still do not know that the covenant exists, or little about it, suggesting better promotion may be needed.